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Sample records for wnt signaling transiently

  1. WNT signalling and haematopoiesis: a WNT-WNT situation.

    NARCIS (Netherlands)

    Staal, F.J.T.; Clevers, J.C.

    2005-01-01

    The evolutionarily conserved WNT-signalling pathway has pivotal roles during the development of many organ systems, and dysregulated WNT signalling is a key factor in the initiation of various tumours. Recent studies have implicated a role for WNT signal transduction at several stages of lymphocyte

  2. Wnt Signaling and Colorectal Cancer.

    Science.gov (United States)

    Schatoff, Emma M; Leach, Benjamin I; Dow, Lukas E

    2017-04-01

    The WNT signaling pathway is a critical mediator of tissue homeostasis and repair, and frequently co-opted during tumor development. Almost all colorectal cancers (CRC) demonstrate hyperactivation of the WNT pathway, which in many cases is believed to be the initiating and driving event. In this short review, we provide a focused overview of recent developments in our understanding of the WNT pathway in CRC, describe new research tools that are enabling a deeper understanding of WNT biology, and outline ongoing efforts to target this pathway therapeutically.

  3. Wnt signaling during cochlear development.

    Science.gov (United States)

    Munnamalai, Vidhya; Fekete, Donna M

    2013-05-01

    Wnt signaling is a hallmark of all embryonic development with multiple roles at multiple developmental time points. Wnt signaling is also important in the development of several organs, one of which is the inner ear, where it participates in otic specification, the formation of vestibular structures, and the development of the cochlea. In particular, we focus on Wnt signaling in the auditory organ, the cochlea. Attempting to dissect the multiple Wnt signaling pathways in the mammalian cochlea is a challenging task due to limited expression data, particularly at proliferating stages. To offer predictions about Wnt activity, we compare cochlear development with that of other biological systems such as Xenopus retina, brain, cancer cells and osteoblasts. Wnts are likely to regulate development through crosstalk with other signaling pathways, particularly Notch and FGF, leading to changes in the expression of Sox2 and proneural (pro-hair cell) genes. In this review we have consolidated the known signaling pathways in the cochlea with known developmental roles of Wnts from other systems to generate a potential timeline of cochlear development. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Wnt Signaling Is Required for Long-Term Memory Formation

    Directory of Open Access Journals (Sweden)

    Ying Tan

    2013-09-01

    Full Text Available Wnt signaling regulates synaptic plasticity and neurogenesis in the adult nervous system, suggesting a potential role in behavioral processes. Here, we probed the requirement for Wnt signaling during olfactory memory formation in Drosophila using an inducible RNAi approach. Interfering with β-catenin expression in adult mushroom body neurons specifically impaired long-term memory (LTM without altering short-term memory. The impairment was reversible, being rescued by expression of a wild-type β-catenin transgene, and correlated with disruption of a cellular LTM trace. Inhibition of wingless, a Wnt ligand, and arrow, a Wnt coreceptor, also impaired LTM. Wingless expression in wild-type flies was transiently elevated in the brain after LTM conditioning. Thus, inhibiting three key components of the Wnt signaling pathway in adult mushroom bodies impairs LTM, indicating that this pathway mechanistically underlies this specific form of memory.

  5. Wnt5a Signaling in Cancer

    Directory of Open Access Journals (Sweden)

    Marwa S. Asem

    2016-08-01

    Full Text Available Wnt5a is involved in activating several non-canonical WNT signaling pathways, through binding to different members of the Frizzled- and Ror-family receptors. Wnt5a signaling is critical for regulating normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a in regulating cancer cell invasion, metastasis, metabolism and inflammation. In this article, we review findings regarding the molecular mechanisms and roles of Wnt5a signaling in various cancer types, and highlight Wnt5a in ovarian cancer.

  6. [Wnt signaling molecules related to osteoporosis].

    Science.gov (United States)

    Kubota, Takuo; Ozono, Keiichi

    2013-06-01

    Wnt signaling pathway components have been shown to be involved in bone biology since mutations in the LRP5 gene proved to cause osteoporosis-pseudoglioma syndrome and high bone mass trait. Genome wide association studies have indicated that single nucleotide polymorphisms of various components in Wnt signaling pathways are associated with bone mineral density and risk for low-trauma fracture. Mouse genetic studies have demonstrated that multiple components in Wnt signaling pathways play significant roles in skeletal development and bone mass maintenance. Here we review several components in Wnt signaling pathways with their association with bone mineral density in humans.

  7. Wnt signalling pathway parameters for mammalian cells.

    Directory of Open Access Journals (Sweden)

    Chin Wee Tan

    Full Text Available Wnt/β-catenin signalling regulates cell fate, survival, proliferation and differentiation at many stages of mammalian development and pathology. Mutations of two key proteins in the pathway, APC and β-catenin, have been implicated in a range of cancers, including colorectal cancer. Activation of Wnt signalling has been associated with the stabilization and nuclear accumulation of β-catenin and consequential up-regulation of β-catenin/TCF gene transcription. In 2003, Lee et al. constructed a computational model of Wnt signalling supported by experimental data from analysis of time-dependent concentration of Wnt signalling proteins in Xenopus egg extracts. Subsequent studies have used the Xenopus quantitative data to infer Wnt pathway dynamics in other systems. As a basis for understanding Wnt signalling in mammalian cells, a confocal live cell imaging measurement technique is developed to measure the cell and nuclear volumes of MDCK, HEK293T cells and 3 human colorectal cancer cell lines and the concentrations of Wnt signalling proteins β-catenin, Axin, APC, GSK3β and E-cadherin. These parameters provide the basis for formulating Wnt signalling models for kidney/intestinal epithelial mammalian cells. There are significant differences in concentrations of key proteins between Xenopus extracts and mammalian whole cell lysates. Higher concentrations of Axin and lower concentrations of APC are present in mammalian cells. Axin concentrations are greater than APC in kidney epithelial cells, whereas in intestinal epithelial cells the APC concentration is higher than Axin. Computational simulations based on Lee's model, with this new data, suggest a need for a recalibration of the model.A quantitative understanding of Wnt signalling in mammalian cells, in particular human colorectal cancers requires a detailed understanding of the concentrations of key protein complexes over time. Simulations of Wnt signalling in mammalian cells can be initiated

  8. WNT signaling in neuronal maturation and synaptogenesis

    Science.gov (United States)

    Rosso, Silvana B.; Inestrosa, Nibaldo C.

    2013-01-01

    The Wnt signaling pathway plays a role in the development of the central nervous system and growing evidence indicates that Wnts also regulates the structure and function of the adult nervous system. Wnt components are key regulators of a variety of developmental processes, including embryonic patterning, cell specification, and cell polarity. In the nervous system, Wnt signaling also regulates the formation and function of neuronal circuits by controlling neuronal differentiation, axon outgrowth and guidance, dendrite development, synaptic function, and neuronal plasticity. Wnt factors can signal through three very well characterized cascades: canonical or β-catenin pathway, planar cell polarity pathway and calcium pathway that control different processes. However, divergent downstream cascades have been identified to control neuronal morphogenesis. In the nervous system, the expression of Wnt proteins is a highly controlled process. In addition, deregulation of Wnt signaling has been associated with neurodegenerative diseases. Here, we will review different aspects of neuronal and dendrite maturation, including spinogenesis and synaptogenesis. Finally, the role of Wnt pathway components on Alzheimer’s disease will be revised. PMID:23847469

  9. WNT signalling in neuronal maturation and synaptogenesis

    Directory of Open Access Journals (Sweden)

    Silvana Beatriz Rosso

    2013-07-01

    Full Text Available The Wnt signaling pathway plays a role in the development of the central nervous system (CNS and growing evidence indicates that Wnts also regulates the structure and function of the adult nervous system. Wnt components are key regulators of a variety of developmental processes, including embryonic patterning, cell specification, and cell polarity. In the nervous system, Wnt signaling also regulates the formation and function of neuronal circuits by controlling neuronal differentiation, axon outgrowth and guidance, dendrite development, synaptic function and neuronal plasticity. Wnt factors can signal through three very well characterized cascades: canonical or β-catenin pathway, planar cell polarity pathway and calcium pathway that control different processes. However, divergent downstream cascades have been identified to control neuronal morphogenesis. In the nervous system, the expression of Wnt proteins is a highly controlled process. In addition, deregulation of Wnt signaling has been associated with neurodegenerative diseases. Here, we will review different aspects of neuronal and dendrite maturation, including spinogenesis and synaptogenesis. Finally, the role of Wnt pathway components on Alzheimer’s disease will be revised.

  10. Active Wnt signaling in response to cardiac injury

    NARCIS (Netherlands)

    Oerlemans, M.I.; Goumans, M.J.; van Middelaar, B.; Clevers, H.; Doevendans, P.A.; Sluijter, J.P.

    2010-01-01

    Although the contribution of Wnt signaling in infarct healing is suggested, its exact role after myocardial infarction (MI) still needs to be unraveled. We evaluated the cardiac presence of active Wnt signaling in vivo following MI, and investigated in which cell types active Wnt signaling was

  11. Wnt pathway in Dupuytren disease : connecting profibrotic signals

    NARCIS (Netherlands)

    Van Beuge, Marike M.; Ten Dam, Evert-Jan P. M.; Werker, Paul M. N.; Bank, Ruud A.

    2015-01-01

    A role of Wnt signaling in Dupuytren disease, a fibroproliferative disease of the hand and fingers, has not been fully elucidated. We examined a large set of Wnt pathway components and signaling targets and found significant dysregulation of 41 Wnt-related genes in tissue from the Dupuytren nodules

  12. Canonical Wnt signaling is antagonized by noncanonical Wnt5a in hepatocellular carcinoma cells

    Directory of Open Access Journals (Sweden)

    Yilmaz Mustafa

    2009-10-01

    Full Text Available Abstract Background β-catenin mutations that constitutively activate the canonical Wnt signaling have been observed in a subset of hepatocellular carcinomas (HCCs. These mutations are associated with chromosomal stability, low histological grade, low tumor invasion and better patient survival. We hypothesized that canonical Wnt signaling is selectively activated in well-differentiated, but repressed in poorly differentiated HCCs. To this aim, we characterized differentiation status of HCC cell lines and compared their expression status of Wnt pathway genes, and explored their activity of canonical Wnt signaling. Results We classified human HCC cell lines into "well-differentiated" and "poorly differentiated" subtypes, based on the expression of hepatocyte lineage, epithelial and mesenchymal markers. Poorly differentiated cell lines lost epithelial and hepatocyte lineage markers, and overexpressed mesenchymal markers. Also, they were highly motile and invasive. We compared the expression of 45 Wnt pathway genes between two subtypes. TCF1 and TCF4 factors, and LRP5 and LRP6 co-receptors were ubiquitously expressed. Likewise, six Frizzled receptors, and canonical Wnt3 ligand were expressed in both subtypes. In contrast, canonical ligand Wnt8b and noncanonical ligands Wnt4, Wnt5a, Wnt5b and Wnt7b were expressed selectively in well- and poorly differentiated cell lines, respectively. Canonical Wnt signaling activity, as tested by a TCF reporter assay was detected in 80% of well-differentiated, contrary to 14% of poorly differentiated cell lines. TCF activity generated by ectopic mutant β-catenin was weak in poorly differentiated SNU449 cell line, suggesting a repressive mechanism. We tested Wnt5a as a candidate antagonist. It strongly inhibited canonical Wnt signaling that is activated by mutant β-catenin in HCC cell lines. Conclusion Differential expression of Wnt ligands in HCC cells is associated with selective activation of canonical Wnt

  13. Canonical Wnt signaling in differentiated osteoblasts controls osteoclast differentiation.

    NARCIS (Netherlands)

    Glass, D.A.; Bialek, P.; Ahn, J.D.; Starbuck, M.; Patel, M.S.; Clevers, J.C.; Taketo, M.M.; Long, F.; McMahon, A.P.; Lang, R.A.; Karsenty, G.

    2005-01-01

    Inactivation of beta-catenin in mesenchymal progenitors prevents osteoblast differentiation; inactivation of Lrp5, a gene encoding a likely Wnt coreceptor, results in low bone mass (osteopenia) by decreasing bone formation. These observations indicate that Wnt signaling controls osteoblast

  14. Wnt Signaling in Prostate Cancer Bone Metastases

    Science.gov (United States)

    2016-11-01

    Pten, Estrous Cycle MCB - 11 THE EFFECT OF HDACI (AR-42) ON CANINE PROSTATE CANCER METASTASIS. S. Elshafae1, N. Kohart1, L... canine prostate cancer overexpressing Dkk-1 was used in this study to investigate how enhanced Wnt/JNK signaling could alter tumor growth, metastasis and...metastatic phenotype of prostate cancer. Ace-1-Dkk-1, a canine prostate cancer overexpressing human Dkk-1, previously developed in our lab was used in

  15. Wnt Signaling in Renal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Qi Xu

    2016-06-01

    Full Text Available Renal cell carcinoma (RCC accounts for 90% of all kidney cancers. Due to poor diagnosis, high resistance to the systemic therapies and the fact that most RCC cases occur sporadically, current research switched its focus on studying the molecular mechanisms underlying RCC. The aim is the discovery of new effective and less toxic anti-cancer drugs and novel diagnostic markers. Besides the PI3K/Akt/mTOR, HGF/Met and VHL/hypoxia cellular signaling pathways, the involvement of the Wnt/β-catenin pathway in RCC is commonly studied. Wnt signaling and its targeted genes are known to actively participate in different biological processes during embryonic development and renal cancer. Recently, studies have shown that targeting this pathway by alternating/inhibiting its intracellular signal transduction can reduce cancer cells viability and inhibit their growth. The targets and drugs identified show promising potential to serve as novel RCC therapeutics and prognostic markers. This review aims to summarize the current status quo regarding recent research on RCC focusing on the involvement of the Wnt/β-catenin pathway and how its understanding could facilitate the identification of potential therapeutic targets, new drugs and diagnostic biomarkers.

  16. Augmenting endogenous Wnt signaling improves skin wound healing

    National Research Council Canada - National Science Library

    Whyte, Jemima L; Smith, Andrew A; Liu, Bo; Manzano, Wilfred R; Evans, Nick D; Dhamdhere, Girija R; Fang, Mark Y; Chang, Howard Y; Oro, Anthony E; Helms, Jill A

    2013-01-01

    .... Utilizing a biochemical approach that mimics the amplified Wnt response of Axin2(LacZ/LacZ) mice, we show that topical application of liposomal Wnt3a to a non-healing wound enhances endogenous Wnt signaling, and results in better skin wound healing...

  17. Wnt expression and canonical Wnt signaling in human bone marrow B lymphopoiesis

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    Funderud Steinar

    2006-06-01

    Full Text Available Abstract Background The early B lymphopoiesis in mammals is regulated through close interactions with stromal cells and components of the intracellular matrix in the bone marrow (BM microenvironment. Although B lymphopoiesis has been studied for decades, the factors that are implicated in this process, both autocrine and paracrine, are inadequately explored. Wnt signaling is known to be involved in embryonic development and growth regulation of tissues and cancer. Wnt molecules are produced in the BM, and we here ask whether canonical Wnt signaling has a role in regulating human BM B lymphopoiesis. Results Examination of the mRNA expression pattern of Wnt ligands, Fzd receptors and Wnt antagonists revealed that BM B progenitor cells and stromal cells express a set of ligands and receptors available for induction of Wnt signaling as well as antagonists for fine tuning of this signaling. Furthermore, different B progenitor maturation stages showed differential expression of Wnt receptors and co-receptors, β-catenin, plakoglobin, LEF-1 and TCF-4 mRNAs, suggesting canonical Wnt signaling as a regulator of early B lymphopoiesis. Exogenous Wnt3A induced stabilization and nuclear accumulation of β-catenin in primary lineage restricted B progenitor cells. Also, Wnt3A inhibited B lymphopoiesis of CD133+CD10- hematopoietic progenitor cells and CD10+ B progenitor cells in coculture assays using a supportive layer of stromal cells. This effect was blocked by the Wnt antagonists sFRP1 or Dkk1. Examination of early events in the coculture showed that Wnt3A inhibits cell division of B progenitor cells. Conclusion These results indicate that canonical Wnt signaling is involved in human BM B lymphopoiesis where it acts as a negative regulator of cell proliferation in a direct or stroma dependent manner.

  18. Renal hypodysplasia associates with a WNT4 variant that causes aberrant canonical WNT signaling.

    Science.gov (United States)

    Vivante, Asaf; Mark-Danieli, Michal; Davidovits, Miriam; Harari-Steinberg, Orit; Omer, Dorit; Gnatek, Yehudit; Cleper, Roxana; Landau, Daniel; Kovalski, Yael; Weissman, Irit; Eisenstein, Israel; Soudack, Michalle; Wolf, Haike Reznik; Issler, Naomi; Lotan, Danny; Anikster, Yair; Dekel, Benjamin

    2013-03-01

    Abnormal differentiation of the renal stem/progenitor pool into kidney tissue can lead to renal hypodysplasia (RHD), but the underlying causes of RHD are not well understood. In this multicenter study, we identified 20 Israeli pedigrees with isolated familial, nonsyndromic RHD and screened for mutations in candidate genes involved in kidney development, including PAX2, HNF1B, EYA1, SIX1, SIX2, SALL1, GDNF, WNT4, and WT1. In addition to previously reported RHD-causing genes, we found that two affected brothers were heterozygous for a missense variant in the WNT4 gene. Functional analysis of this variant revealed both antagonistic and agonistic canonical WNT stimuli, dependent on cell type. In HEK293 cells, WNT4 inhibited WNT3A induced canonical activation, and the WNT4 variant significantly enhanced this inhibition of the canonical WNT pathway. In contrast, in primary cultures of human fetal kidney cells, which maintain WNT activation and more closely represent WNT signaling in renal progenitors during nephrogenesis, this mutation caused significant loss of function, resulting in diminished canonical WNT/β-catenin signaling. In conclusion, heterozygous WNT4 variants are likely to play a causative role in renal hypodysplasia.

  19. Wnt signaling, stem cells, and cancer of the gastrointestinal tract

    NARCIS (Netherlands)

    Schepers, A.; Clevers, H.

    2012-01-01

    The Wnt signaling pathway was originally uncovered as one of the prototype developmental signaling cascades in invertebrates as well as in vertebrates. The first indication that Wnt signaling also plays a role in the adult animal came from the study of the intestine of Tcf-4 (Tcf7L2) knockout mice.

  20. Surrogate Wnt agonists that phenocopy canonical Wnt and β-catenin signalling

    NARCIS (Netherlands)

    Janda, Claudia Y; Dang, Luke T; You, Changjiang; Chang, Junlei; de Lau, Wim; Zhong, Zhendong A; Yan, Kelley S; Marecic, Owen; Siepe, Dirk; Li, Xingnan; Moody, James D; Williams, Bart O; Clevers, Hans; Piehler, Jacob; Baker, David; Kuo, Calvin J; Garcia, K Christopher

    2017-01-01

    Wnt proteins modulate cell proliferation and differentiation and the self-renewal of stem cells by inducing β-catenin-dependent signalling through the Wnt receptor frizzled (FZD) and the co-receptors LRP5 and LRP6 to regulate cell fate decisions and the growth and repair of several tissues. The 19

  1. WNT-er is coming’: WNT signalling in chronic lung diseases

    Science.gov (United States)

    Baarsma, H A

    2017-01-01

    Chronic lung diseases represent a major public health problem with only limited therapeutic options. An important unmet need is to identify compounds and drugs that target key molecular pathways involved in the pathogenesis of chronic lung diseases. Over the last decade, there has been extensive interest in investigating Wingless/integrase-1 (WNT) signalling pathways; and WNT signal alterations have been linked to pulmonary disease pathogenesis and progression. Here, we comprehensively review the cumulative evidence for WNT pathway alterations in chronic lung pathologies, including idiopathic pulmonary fibrosis, pulmonary arterial hypertension, asthma and COPD. While many studies have focused on the canonical WNT/β-catenin signalling pathway, recent reports highlight that non-canonical WNT signalling may also significantly contribute to chronic lung pathologies; these studies will be particularly featured in this review. We further discuss recent advances uncovering the role of WNT signalling early in life, the potential of pharmaceutically modulating WNT signalling pathways and highlight (pre)clinical studies describing promising new therapies for chronic lung diseases. PMID:28416592

  2. Wnt Signaling in Stem Cells and Tumor Stem Cells.

    Science.gov (United States)

    Kahn, Michael

    2015-09-01

    The Wnt signaling cascade is critically important in stem cell biology, both in homeostatic maintenance and repair and regeneration of tissues and organs, through their respective somatic stem cells (SSCs). However, aberrant Wnt signaling is associated with a wide array of tumor types and Wnt signaling is important in the so-termed cancer stem cell/tumor-initiating cell (CSC/TIC) population. The ability to safely therapeutically target the Wnt signaling pathway offers enormous promise. However, just like the Sword of Damocles, significant risks and concerns regarding targeting such a critical pathway in normal stem cell maintenance and tissue homeostasis remain ever present. With this in mind, we review our current understanding of the role of Wnt signaling in SSCs and CSC/TICs and the potential to pharmacologically manipulate these endogenous stem cell populations (both normal and tumor). Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  3. Wnt Signaling Pathway and Its Significance for Melanoma Development

    OpenAIRE

    Kulikova К.V.; Kibardin А.V.; Gnuchev N.V.; Georgiev G.P.; Larin S.S.

    2012-01-01

    Melanoma is characterized by its high metastatic propensity. Melanoma metastasis is associated with an activation of signaling pathways that are responsible for embryogenesis. Wnt signaling pathway is considered as one of the key signaling cascades, whose aberrant activation results in melanoma development. Wnt signaling includes a complex network of intracellular interactions. Its ligands are able to initiate at least three signal transduction pathways: canonical and two noncanonical. Accord...

  4. Neural crest specification by noncanonical Wnt signaling and PAR-1

    Science.gov (United States)

    Ossipova, Olga; Sokol, Sergei Y.

    2011-01-01

    Neural crest (NC) cells are multipotent progenitors that form at the neural plate border, undergo epithelial-mesenchymal transition and migrate to diverse locations in vertebrate embryos to give rise to many cell types. Multiple signaling factors, including Wnt proteins, operate during early embryonic development to induce the NC cell fate. Whereas the requirement for the Wnt/β-catenin pathway in NC specification has been well established, a similar role for Wnt proteins that do not stabilize β-catenin has remained unclear. Our gain- and loss-of-function experiments implicate Wnt11-like proteins in NC specification in Xenopus embryos. In support of this conclusion, modulation of β-catenin-independent signaling through Dishevelled and Ror2 causes predictable changes in premigratory NC. Morpholino-mediated depletion experiments suggest that Wnt11R, a Wnt protein that is expressed in neuroectoderm adjacent to the NC territory, is required for NC formation. Wnt11-like signals might specify NC by altering the localization and activity of the serine/threonine polarity kinase PAR-1 (also known as microtubule-associated regulatory kinase or MARK), which itself plays an essential role in NC formation. Consistent with this model, PAR-1 RNA rescues NC markers in embryos in which noncanonical Wnt signaling has been blocked. These experiments identify novel roles for Wnt11R and PAR-1 in NC specification and reveal an unexpected connection between morphogenesis and cell fate. PMID:22110058

  5. Crosstalk between Wnt Signaling and RNA Processing in Colorectal Cancer

    Directory of Open Access Journals (Sweden)

    Michael Bordonaro

    2013-01-01

    Full Text Available RNA processing involves a variety of processes affecting gene expression, including the removal of introns through RNA splicing, as well as 3' end processing (cleavage and polyadenylation. Alternative RNA processing is fundamentally important for gene regulation, and aberrant processing is associated with the initiation and progression of cancer. Deregulated Wnt signaling, which is the initiating event in the development of most cases of human colorectal cancer (CRC, has been linked to modified RNA processing, which may contribute to Wnt-mediated colonic carcinogenesis. Crosstalk between Wnt signaling and alternative RNA splicing with relevance to CRC includes effects on the expression of Rac1b, an alternatively spliced gene associated with tumorigenesis, which exhibits alternative RNA splicing that is influenced by Wnt activity. In addition, Tcf4, a crucial component of Wnt signaling, also exhibits alternative splicing, which is likely involved in colonic tumorigenesis. Modulation of 3' end formation, including of the Wnt target gene COX-2, also can influence the neoplastic process, with implications for CRC. While many human genes are dependent on introns and splicing for normal levels of gene expression, naturally intronless genes exist with a unique metabolism that allows for intron-independent gene expression. Effects of Wnt activity on the RNA metabolism of the intronless Wnt-target gene c-jun is a likely contributor to cancer development. Further, butyrate, a breakdown product of dietary fiber and a histone deacetylase inhibitor, upregulates Wnt activity in CRC cells, and also modulates RNA processing; therefore, the interplay between Wnt activity, the modulation of this activity by butyrate, and differential RNA metabolism in colonic cells can significantly influence tumorigenesis. Determining the role played by altered RNA processing in Wnt-mediated neoplasia may lead to novel interventions aimed at restoring normal RNA metabolism for

  6. Roles of Wnt signaling in bone formation and resorption

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    Yasuhiro Kobayashi

    2008-07-01

    Full Text Available Wnt proteins (Wnts are palmitoylated and glycosylated ligands that play a central role in the early development of organs and tissues. The discovery that loss-of-function mutations in low density lipoprotein receptor-related protein 5 (LRP5, a Wnt co-receptor, led to low bone mass in humans revealed the possible role of Wnt signaling in the regulation of bone remodeling. Many findings obtained from detailed analyses of mice having mutations of Wnt signaling molecules have confirmed that Wnt signaling has potential roles in bone remodeling in both physiological and pathological conditions. There are two pathways of Wnt signaling: β-catenin-dependent canonical and -independent non-canonical pathways. Wnts act on osteoblast precursor cells and promote their differentiation into mature osteoblasts through the β-catenin-dependent canonical pathway. In addition, Wnts suppress bone resorption by regulating the receptor activator of NF-κB ligand (RANKL/osteoprotegerin (OPG ratio through the same pathway in mature osteoblasts. In contrast, recent studies have shown that the activation of the β-catenin-independent non-canonical pathway enhances the RANKL-induced osteoclast formation in mouse macrophage cultures. These results indicate that Wnt-mediated signals are involved in several aspects of bone formation and bone resorption. This review will summarize the current knowledge of the roles of Wnt signaling in bone formation and resorption.

  7. Functional Wnt signaling is increased in idiopathic pulmonary fibrosis.

    Directory of Open Access Journals (Sweden)

    Melanie Königshoff

    Full Text Available BACKGROUND: Idiopathic pulmonary fibrosis (IPF is a fatal lung disease, characterized by distorted lung architecture and loss of respiratory function. Alveolar epithelial cell injury and hyperplasia, enhanced extracellular matrix deposition, and (myofibroblast activation are features of IPF. Wnt/beta-catenin signaling has been shown to determine epithelial cell fate during development. As aberrant reactivation of developmental signaling pathways has been suggested to contribute to IPF pathogenesis, we hypothesized that Wnt/beta-catenin signaling is activated in epithelial cells in IPF. Thus, we quantified and localized the expression and activity of the Wnt/beta-catenin pathway in IPF. METHODOLOGY/PRINCIPAL FINDINGS: The expression of Wnt1, 3a, 7b, and 10b, the Wnt receptors Fzd1-4, Lrp5-6, as well as the intracellular signal transducers Gsk-3beta, beta-catenin, Tcf1, 3, 4, and Lef1 was analyzed in IPF and transplant donor lungs by quantitative real-time (qRT-PCR. Wnt1, 7b and 10b, Fzd2 and 3, beta-catenin, and Lef1 expression was significantly increased in IPF. Immunohistochemical analysis localized Wnt1, Wnt3a, beta-catenin, and Gsk-3beta expression largely to alveolar and bronchial epithelium. This was confirmed by qRT-PCR of primary alveolar epithelial type II (ATII cells, demonstrating a significant increase of Wnt signaling in ATII cells derived from IPF patients. In addition, Western blot analysis of phospho-Gsk-3beta, phospho-Lrp6, and beta-catenin, and qRT-PCR of the Wnt target genes cyclin D1, Mmp 7, or Fibronectin 1 demonstrated increased functional Wnt/beta-catenin signaling in IPF compared with controls. Functional in vitro studies further revealed that Wnt ligands induced lung epithelial cell proliferation and (myofibroblast activation and collagen synthesis. CONCLUSIONS/SIGNIFICANCE: Our study demonstrates that the Wnt/beta-catenin pathway is expressed and operative in adult lung epithelium. Increased Wnt/beta-catenin signaling

  8. Wnt pathway in Dupuytren disease: connecting profibrotic signals.

    Science.gov (United States)

    van Beuge, Marike M; Ten Dam, Evert-Jan P M; Werker, Paul M N; Bank, Ruud A

    2015-12-01

    A role of Wnt signaling in Dupuytren disease, a fibroproliferative disease of the hand and fingers, has not been fully elucidated. We examined a large set of Wnt pathway components and signaling targets and found significant dysregulation of 41 Wnt-related genes in tissue from the Dupuytren nodules compared with patient-matched control tissue. A large proportion of genes coding for Wnt proteins themselves was downregulated. However, both canonical Wnt targets and components of the noncanonical signaling pathway were upregulated. Immunohistochemical analysis revealed that protein expression of Wnt1-inducible secreted protein 1 (WISP1), a known Wnt target, was increased in nodules compared with control tissue, but knockdown of WISP1 using small interfering RNA (siRNA) in the Dupuytren myofibroblasts did not confirm a functional role. The protein expression of noncanonical pathway components Wnt5A and VANGL2 as well as noncanonical coreceptors Ror2 and Ryk was increased in nodules. On the contrary, the strongest downregulated genes in this study were 4 antagonists of Wnt signaling (DKK1, FRZB, SFRP1, and WIF1). Downregulation of these genes in the Dupuytren tissue was mimicked in vitro by treating normal fibroblasts with transforming growth factor β1 (TGF-β1), suggesting cross talk between different profibrotic pathways. Furthermore, siRNA-mediated knockdown of these antagonists in normal fibroblasts led to increased nuclear translocation of Wnt target β-catenin in response to TGF-β1 treatment. In conclusion, we have shown extensive dysregulation of Wnt signaling in affected tissue from Dupuytren disease patients. Components of both the canonical and the noncanonical pathways are upregulated, whereas endogenous antagonists are downregulated, possibly via interaction with other profibrotic pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Canonical WNT signaling pathway and human AREG.

    Science.gov (United States)

    Katoh, Yuriko; Katoh, Masaru

    2006-06-01

    AREG (Amphiregulin), BTC (beta-cellulin), EGF, EPGN (Epigen), EREG (Epiregulin), HBEGF, NRG1, NRG2, NRG3, NRG4 and TGFA (TGFalpha) constitute EGF family ligands for ERBB family receptors. Cetuximab (Erbitux), Pertuzumab (Omnitarg) and Trastuzumab (Herceptin) are anti-cancer drugs targeted to EGF family ligands, while Gefitinib (Iressa), Erlotinib (Tarceva) and Lapatinib (GW572016) are anti-cancer drugs targeted to ERBB family receptors. AREG and TGFA are biomarkers for Gefitinib non-responders. The TCF/LEF binding sites within the promoter region of human EGF family members were searched for by using bioinformatics and human intelligence (Humint). Because three TCF/LEF-binding sites were identified within the 5'-promoter region of human AREG gene, comparative genomics analyses on AREG orthologs were further performed. The EPGN-EREG-AREG-BTC cluster at human chromosome 4q13.3 was linked to the PPBP-CXCL segmental duplicons. AREG was the paralog of HBEGF at human chromosome 5q31.2. Chimpanzee AREG gene, consisting of six exons, was located within NW_105918.1 genome sequence. Chimpanzee AREG was a type I transmembrane protein showing 98.0% and 71.4% total amino-acid identity with human AREG and mouse Areg, respectively. Three TCF/LEF-binding sites within human AREG promoter were conserved in chimpanzee AREG promoter, but not in rodent Areg promoters. Primate AREG promoters were significantly divergent from rodent Areg promoters. AREG mRNA was expressed in a variety of human tumors, such as colorectal cancer, liver cancer, gastric cancer, breast cancer, prostate cancer, esophageal cancer and myeloma. Because human AREG was characterized as potent target gene of WNT/beta-catenin signaling pathway, WNT signaling activation could lead to Gefitinib resistance through AREG upregulation. AREG is a target of systems medicine in the field of oncology.

  10. Cross-talk between insulin and Wnt signaling in preadipocytes

    DEFF Research Database (Denmark)

    Palsgaard, Jane; Emanuelli, Brice; Winnay, Jonathon N

    2012-01-01

    Disturbed Wnt signaling has been implicated in numerous diseases, including type 2 diabetes and the metabolic syndrome. In the present study, we have investigated cross-talk between insulin and Wnt signaling pathways using preadipocytes with and without knockdown of the Wnt co-receptors LRP5...... are insulin/IGF-1 receptor-dependent and are lost in insulin/IGF-1 receptor double knock-out cells. Conversely, in LRP5 knockdown preadipocytes, insulin-induced phosphorylation of IRS1, Akt, GSK3β, and ERK1/2 is highly reduced. This effect is specific to insulin, as compared with IGF-1, stimulation...... and appears to be due to an inducible interaction between LRP5 and the insulin receptor as demonstrated by co-immunoprecipitation. These data demonstrate that Wnt and insulin signaling pathways exhibit cross-talk at multiple levels. Wnt induces phosphorylation of Akt, ERK1/2, and GSK3β, and this is dependent...

  11. Wnt Signaling Cascades and the Roles of Syndecan Proteoglycans

    DEFF Research Database (Denmark)

    Pataki, Csilla A; Couchman, John R; Brábek, Jan

    2015-01-01

    /planar cell polarity and Wnt/calcium signaling. Syndecans are type I transmembrane proteoglycans with a long evolutionary history, being expressed in all Bilateria and in almost all cell types. Both Wnt pathways have been extensively studied over the past 30 years and shown to have roles during development...

  12. Wnt signaling, de novo lipogenesis, adipogenesis and ectopic fat

    National Research Council Canada - National Science Library

    Song, Kangxing; Wang, Shuxia; Mani, Mitra; Mani, Arya

    2014-01-01

    ...). Following we will describe our most pertinent findings related to Wnt/LRP6 regulation of de novo lipogenesis and adipogenesis and the role of impaired Wnt signaling in generation of ectopic fat, insulin resistance, elevated plasma lipids and non-alcoholic fatty liver disease (NAFLD).

  13. Wnt signaling inhibits osteogenic differentiation of human mesenchymal stem cells

    NARCIS (Netherlands)

    de Boer, Jan; Siddappa, R.; Gaspar, Claudia; van Apeldoorn, Aart A.; Fodde, Riccardo; van Blitterswijk, Clemens

    2004-01-01

    Human mesenchymal stem cells (hMSCs) from the bone marrow represent a potential source of pluripotent cells for autologous bone tissue engineering. We previously discovered that over activation of the Wnt signal transduction pathway by either lithium or Wnt3A stimulates hMSC proliferation while

  14. Wnt/β-Catenin Signaling, Disease, and Emerging Therapeutic Modalities

    NARCIS (Netherlands)

    Nusse, Roel; Clevers, Hans

    2017-01-01

    The WNT signal transduction cascade is a main regulator of development throughout the animal kingdom. Wnts are also key drivers of most types of tissue stem cells in adult mammals. Unsurprisingly, mutated Wnt pathway components are causative to multiple growth-related pathologies and to cancer.

  15. Wnt signaling induces epithelial differentiation during cutaneous wound healing

    Directory of Open Access Journals (Sweden)

    Hocking Anne

    2006-01-01

    Full Text Available Abstract Background Cutaneous wound repair in adult mammals does not regenerate the original epithelial architecture and results in altered skin function. We propose that lack of regeneration may be due to the absence of appropriate molecular signals to promote regeneration. In this study, we investigated the regulation of Wnt signaling during cutaneous wound healing and the consequence of activating either the beta-catenin-dependent or beta-catenin-independent Wnt signaling on epidermal architecture during wound repair. Results We determined that the expression of Wnt ligands that typically signal via the beta-catenin-independent pathway is up-regulated in the wound while the beta-catenin-dependent Wnt signaling is activated in the hair follicles adjacent to the wound edge. Ectopic activation of beta-catenin-dependent Wnt signaling with lithium chloride in the wound resulted in epithelial cysts and occasional rudimentary hair follicle structures within the epidermis. In contrast, forced expression of Wnt-5a in the deeper wound induced changes in the interfollicular epithelium mimicking regeneration, including formation of epithelia-lined cysts in the wound dermis, rudimentary hair follicles and sebaceous glands, without formation of tumors. Conclusion These findings suggest that adult interfollicular epithelium is capable of responding to Wnt morphogenic signals necessary for restoring epithelial tissue patterning in the skin during wound repair.

  16. Wnt signaling in the thymus is regulated by differential expression of intracellular signaling molecules.

    NARCIS (Netherlands)

    F. Weerkamp (Floor); M.R.M. Baert (Miranda); B.A. Naber (Brigitta); E.E. Koster (Esther); E.F. de Haas (Edwin); K.R. Atkuri (Kondala); J.J.M. van Dongen (Jacques); L.A. Herzenberg (Leonard); F.J.T. Staal (Frank)

    2006-01-01

    textabstractWnt signaling is essential for T cell development in the thymus, but the stages in which it occurs and the molecular mechanisms underlying Wnt responsiveness have remained elusive. Here we examined Wnt signaling activity in both human and murine thymocyte populations by determining

  17. Non-canonical wnt Signals Antagonize and Canonical wnt Signals Promote Cell Proliferation in Early Kidney Development

    OpenAIRE

    McCoy, Kyle E.; Zhou, Xiaolan; Vize, Peter D.

    2011-01-01

    Canonical and non-canonical wnt signals often have opposed roles. In this report, we use developing Xenopus embryos to demonstrate a novel anti-proliferative role for non-canonical wnt signals in the very earliest stages of kidney development. Non-canonical wnt signals were down-regulated using PDZ domain mutants of dishevelled 2 and up-regulated using wild-type vang-like 2, while canonical signals were manipulated using dominant-negative forms of lef1 or treatment with lithium. When non-cano...

  18. Canonical Wnt Signaling Regulates Atrioventricular Junction Programming and Electrophysiological Properties

    Science.gov (United States)

    Gillers, Benjamin S; Chiplunkar, Aditi; Aly, Haytham; Valenta, Tomas; Basler, Konrad; Christoffels, Vincent M.; Efimov, Igor R; Boukens, Bastiaan J; Rentschler, Stacey

    2014-01-01

    Rationale Proper patterning of the atrioventricular canal (AVC) is essential for delay of electrical impulses between atria and ventricles, and defects in AVC maturation can result in congenital heart disease. Objective To determine the role of canonical Wnt signaling in the myocardium during AVC development. Methods and Results We utilized a novel allele of β-catenin that preserves β-catenin’s cell adhesive functions but disrupts canonical Wnt signaling, allowing us to probe the effects of Wnt loss of function independently. We show that loss of canonical Wnt signaling in the myocardium results in tricuspid atresia with hypoplastic right ventricle associated with loss of AVC myocardium. In contrast, ectopic activation of Wnt signaling was sufficient to induce formation of ectopic AV junction-like tissue as assessed by morphology, gene expression, and electrophysiologic criteria. Aberrant AVC development can lead to ventricular preexcitation, a characteristic feature of Wolff-Parkinson-White syndrome. We demonstrate that postnatal activation of Notch signaling downregulates canonical Wnt targets within the AV junction. Stabilization of β-catenin protein levels can rescue Notch-mediated ventricular preexcitation and dysregulated ion channel gene expression. Conclusions Our data demonstrate that myocardial canonical Wnt signaling is an important regulator of AVC maturation and electrical programming upstream of Tbx3. Our data further suggests that ventricular preexcitation may require both morphologic patterning defects, as well as myocardial lineage reprogramming, to allow robust conduction across accessory pathway tissue. PMID:25599332

  19. Non-canonical wnt signals antagonize and canonical wnt signals promote cell proliferation in early kidney development.

    Science.gov (United States)

    McCoy, Kyle E; Zhou, Xiaolan; Vize, Peter D

    2011-06-01

    Canonical and non-canonical wnt signals often have opposed roles. In this report, we use developing Xenopus embryos to demonstrate a novel anti-proliferative role for non-canonical wnt signals in the very earliest stages of kidney development. Non-canonical wnt signals were down-regulated using PDZ domain mutants of dishevelled 2 and up-regulated using wild-type vang-like 2, while canonical signals were manipulated using dominant-negative forms of lef1 or treatment with lithium. When non-canonical signals are down-regulated in the developing Xenopus pronephros, cell proliferation rates increased and when canonical signals were shutdown the opposite occurred. Treatment with lithium chloride has a powerful pro-proliferative effect on the forming nephric primordium. Together these data show that in addition to previously documented antagonisms between these distinct wnt signaling pathways, they also have opposing effects on cell division. Copyright © 2011 Wiley-Liss, Inc.

  20. Effect of Wnt-1 inducible signaling pathway protein-2 (WISP-2/CCN5), a downstream protein of Wnt signaling, on adipocyte differentiation.

    Science.gov (United States)

    Inadera, Hidekuni; Shimomura, Akiko; Tachibana, Shinjiro

    2009-02-20

    Wnt signaling negatively regulates adipocyte differentiation, and ectopic expression of Wnt-1 in 3T3-L1 cells induces several downstream molecules of Wnt signaling, including Wnt-1 inducible signaling pathway protein (WISP)-2. In this study, we examined the role of WISP-2 in the process of adipocyte differentiation using an in vitro cell culture system. In the differentiation of 3T3-L1 cells, WISP-2 expression was observed in growing cells and declined thereafter. In the mitotic clonal expansion phase of adipocyte differentiation, WISP-2 expression was transiently down-regulated concurrently with up-regulation of CCAAT/enhancer-binding protein delta expression. Treatment of 3T3-L1 cells in the differentiation medium with lithium, an activator of Wnt signaling, inhibited the differentiation process with concomitant induction of WISP-2. Treatment of differentiated cells with lithium induced de-differentiation as evidenced by profound reduction of peroxisome proliferator-activator receptor gamma expression and concomitant induction of WISP-2. However, de-differentiation of differentiated cells induced by tumor necrosis factor-alpha did not induce WISP-2 expression. To directly examine the effect of WISP-2 on adipocyte differentiation, 3T3-L1 cells were infected with a retrovirus carrying WISP-2. Although forced expression of WISP-2 inhibited preadipocyte proliferation, it had no effect on adipocyte differentiation. Thus, although WISP-2 is a downstream protein of Wnt signaling, the role of WISP-2 on adipocyte differentiation may be marginal, at least in this in vitro culture model.

  1. Hypothalamic Wnt Signalling and its Role in Energy Balance Regulation.

    Science.gov (United States)

    Helfer, G; Tups, A

    2016-03-01

    Wnt signalling and its downstream effectors are well known for their roles in embryogenesis and tumourigenesis, including the regulation of cell proliferation, survival and differentiation. In the nervous system, Wnt signalling has been described mainly during embryonic development, although accumulating evidence suggests that it also plays a major role in adult brain morphogenesis and function. Studies have predominantly concentrated on memory formation in the hippocampus, although recent data indicate that Wnt signalling is also critical for neuroendocrine control of the developed hypothalamus, a brain centre that is key in energy balance regulation and whose dysfunction is implicated in metabolic disorders such as type 2 diabetes and obesity. Based on scattered findings that report the presence of Wnt molecules in the tanycytes and ependymal cells lining the third ventricle and arcuate nucleus neurones of the hypothalamus, their potential importance in key regions of food intake and body weight regulation has been investigated in recent studies. The present review brings together current knowledge on Wnt signalling in the hypothalamus of adult animals and discusses the evidence suggesting a key role for members of the Wnt signalling family in glucose and energy balance regulation in the hypothalamus in diet-induced and genetically obese (leptin deficient) mice. Aspects of Wnt signalling in seasonal (photoperiod sensitive) rodents are also highlighted, given the recent evidence indicating that the Wnt pathway in the hypothalamus is not only regulated by diet and leptin, but also by photoperiod in seasonal animals, which is connected to natural adaptive changes in food intake and body weight. Thus, Wnt signalling appears to be critical as a modulator for normal functioning of the physiological state in the healthy adult brain, and is also crucial for normal glucose and energy homeostasis where its dysregulation can lead to a range of metabolic disorders. © 2016

  2. Wnt signaling in the early sea urchin embryo.

    Science.gov (United States)

    Kumburegama, Shalika; Wikramanayake, Athula H

    2008-01-01

    Wnt signaling regulates a remarkably diverse array of cellular and developmental events during animal embryogenesis and homeostasis. The crucial role that Wnt signaling plays in regulating axial patterning in early embryos has been particularly striking. Recent work has highlighted the conserved role that canonical Wnt signaling plays in patterning the animal-vegetal (A-V) axis in sea urchin and sea anemone embryos. In sea urchin embryos, the canonical Wnt signaling pathway is selectively turned on in vegetal cells as early as the 16-cell stage embryo, and signaling through this pathway is required for activation of the endomesodermal gene regulatory network. Loss of nuclear beta-catenin signaling animalizes the sea urchin embryo and blocks pattern formation along the entire A-V axis. Nuclear entry of beta-catenin into vegetal cells is regulated cell autonomously by maternal information that is present at the vegetal pole of the unfertilized egg. Analysis of Dishevelled (Dsh) regulation along the A-V axis has revealed the presence of a cytoarchitectural domain at the vegetal pole of the unfertilized sea urchin egg. This vegetal cortical domain appears to be crucial for the localized activation of Dsh at the vegetal pole, but the precise mechanisms are unknown. The elucidation of how Dsh is selectively activated at the vegetal cortical domain is likely to provide important insight into how this enigmatic protein is regulated during canonical Wnt signaling. Additionally, this information will shed light on the origins of embryonic polarity during animal evolution. This chapter examines the roles played by the canonical Wnt signaling pathway in the specification and patterning of the A-V axis in the sea urchin. These studies have led to the identification of a novel role for canonical Wnt signaling in regulating protein stability, and continued studies of Wnt signaling in this model system are likely to reveal additional roles for this pathway in regulating early

  3. Wnt signaling regulates pulp volume and dentin thickness.

    Science.gov (United States)

    Lim, Won Hee; Liu, Bo; Cheng, Du; Hunter, Daniel J; Zhong, Zhendong; Ramos, Daniel M; Williams, Bart O; Sharpe, Paul T; Bardet, Claire; Mah, Su-Jung; Helms, Jill A

    2014-04-01

    Odontoblasts, cementoblasts, ameloblasts, and osteoblasts all form mineralized tissues in the craniofacial complex, and all these cell types exhibit active Wnt signaling during postnatal life. We set out to understand the functions of this Wnt signaling, by evaluating the phenotypes of mice in which the essential Wnt chaperone protein, Wntless was eliminated. The deletion of Wls was restricted to cells expressing Osteocalcin (OCN), which in addition to osteoblasts includes odontoblasts, cementoblasts, and ameloblasts. Dentin, cementum, enamel, and bone all formed in OCN-Cre;Wls(fl/fl) mice but their homeostasis was dramatically affected. The most notable feature was a significant increase in dentin volume and density. We attribute this gain in dentin volume to a Wnt-mediated misregulation of Runx2. Normally, Wnt signaling stimulates Runx2, which in turn inhibits dentin sialoprotein (DSP); this inhibition must be relieved for odontoblasts to differentiate. In OCN-Cre;Wls(fl/fl) mice, Wnt pathway activation is reduced and Runx2 levels decline. The Runx2-mediated repression of DSP is relieved and odontoblast differentiation is accordingly enhanced. This study demonstrates the importance of Wnt signaling in the homeostasis of mineralized tissues of the craniofacial complex. © 2014 American Society for Bone and Mineral Research.

  4. Aging in Caenorhabditis elegans; the role of Wnt signalling

    NARCIS (Netherlands)

    Lezzerini, M.

    2015-01-01

    Aging is a universal biological process, broadly characterized by the gradual decline of a multitude of physiological functions, ultimately resulting in organismal death. Wnt signaling is a major and highly conserved developmental pathway that guides many important events during organismal

  5. Deranged Wnt signaling is frequent in hereditary nonpolyposis colorectal cancer

    DEFF Research Database (Denmark)

    Isinger-Ekstrand, Anna; Therkildsen, Christina; Bernstein, Inge

    2011-01-01

    The Wnt signaling pathway is frequently deranged in colorectal cancer and is a key target for future preventive and therapeutic approaches. Colorectal cancers associated with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome are characterized by wide-spread microsatellite instability......, but show few gross genomic alterations. We characterized expression of the Wnt signaling pathway markers β-catenin, E-cadherin, TCF-4, and PTEN using immunohistochemical staining in colorectal cancers from individuals with HNPCC. Reduced membranous staining for β-catenin was found in 64% and for E......% of the tumors. In summary, altered expression of target molecules in the Wnt signaling pathway was demonstrated in the vast majority of the HNPCC-associated tumors, which support deranged Wnt-signaling as a central tumorigenic mechanism also in MMR defective colorectal cancer....

  6. Deranged Wnt signaling is frequent in hereditary nonpolyposis colorectal cancer

    DEFF Research Database (Denmark)

    Isinger-Ekstrand, Anna; Therkildsen, Christina; Bernstein, Inge

    2011-01-01

    The Wnt signaling pathway is frequently deranged in colorectal cancer and is a key target for future preventive and therapeutic approaches. Colorectal cancers associated with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome are characterized by wide-spread microsatellite instability......, but show few gross genomic alterations. We characterized expression of the Wnt signaling pathway markers ß-catenin, E-cadherin, TCF-4, and PTEN using immunohistochemical staining in colorectal cancers from individuals with HNPCC. Reduced membranous staining for ß-catenin was found in 64% and for E......% of the tumors. In summary, altered expression of target molecules in the Wnt signaling pathway was demonstrated in the vast majority of the HNPCC-associated tumors, which support deranged Wnt-signaling as a central tumorigenic mechanism also in MMR defective colorectal cancer....

  7. Frizzled-9 is activated by Wnt-2 and functions in Wnt/beta -catenin signaling.

    Science.gov (United States)

    Karasawa, Takatoshi; Yokokura, Hisayuki; Kitajewski, Jan; Lombroso, Paul J

    2002-10-04

    Frizzled has been known to function as a Wnt receptor. Although there have been a number of mammalian Frizzled members identified, their binding specificities with Wnt and functions in mammalian cells have been poorly understood. Here, we demonstrate that rat Frizzled-9 (Rfz9) functions in Wnt/beta-catenin signaling in 293T cells. Rfz9 overexpression induces the hyperphosphorylation and relocalization of mouse Dishevelled-1 (Dvl-1) from the cytoplasm to the cell membrane and the accumulation of cytosolic beta-catenin. Transfections of Rfz9 with each of several Wnt members show that only Wnt-2 activates Rfz9 in T cell factor (TCF)-dependent transcription. Deletion mutant analysis determines that there is a difference in Rfz9 C-terminal residues required for the modifications of Dvl-1 and those required for the inductions of beta-catenin stabilization and TCF transactivation. Deletion of the Wnt-binding domain does not abolish Rfz9 activity completely, although it causes the inactivation of Wnt-2-dependent TCF transcription. Rfz9 also relocalizes Axin from the cytoplasm to the plasma membrane in the presence of Dvl-1, suggesting that one of the consequences of Dvl-1 relocalization by Rfz9 is to bring Axin to the cell membrane.

  8. Wnt Signaling Is Required for Long-Term Memory Formation

    OpenAIRE

    Tan, Ying; Yu, Dinghui; Busto, Germain U.; Wilson, Curtis; Davis, Ronald L.

    2013-01-01

    Wnt signaling regulates synaptic plasticity and neurogenesis in the adult nervous system, suggesting a potential role in behavioral processes. Here, we probed the requirement for Wnt signaling during olfactory memory formation in Drosophila using an inducible RNA interference approach. Interfering with β-catenin expression in the adult mushroom body neurons specifically impaired long-term memory without altering short-term memory. The impairment was reversible, rescued with expression of a wi...

  9. A critical role for endocytosis in Wnt signaling

    Directory of Open Access Journals (Sweden)

    Nusse Roel

    2006-07-01

    Full Text Available Abstract Background The Wnt signaling pathway regulates many processes during embryonic development, including axis specification, organogenesis, angiogenesis, and stem cell proliferation. Wnt signaling has also been implicated in a number of cancers, bone density maintenance, and neurological conditions during adulthood. While numerous Wnts, their cognate receptors of the Frizzled and Arrow/LRP5/6 families and downstream pathway components have been identified, little is known about the initial events occurring directly after receptor activation. Results We show here that Wnt proteins are rapidly endocytosed by a clathrin- and dynamin-mediated process. While endocytosis has traditionally been considered a principal mechanism for receptor down-regulation and termination of signaling pathways, we demonstrate that interfering with clathrin-mediated endocytosis actually blocks Wnt signaling at the level of β-catenin accumulation and target gene expression. Conclusion A necessary component of Wnt signaling occurs in a subcellular compartment distinct from the plasma membrane. Moreover, as internalized Wnts transit partially through the transferrin recycling pathway, it is possible that a "signaling endosome" serves as a nexus for activated Wnt pathway components.

  10. Disrupting hedgehog and WNT signaling interactions promotes cleft lip pathogenesis

    Science.gov (United States)

    Kurosaka, Hiroshi; Iulianella, Angelo; Williams, Trevor; Trainor, Paul A.

    2014-01-01

    Cleft lip, which results from impaired facial process growth and fusion, is one of the most common craniofacial birth defects. Many genes are known to be involved in the etiology of this disorder; however, our understanding of cleft lip pathogenesis remains incomplete. In the present study, we uncovered a role for sonic hedgehog (SHH) signaling during lip fusion. Mice carrying compound mutations in hedgehog acyltransferase (Hhat) and patched1 (Ptch1) exhibited perturbations in the SHH gradient during frontonasal development, which led to hypoplastic nasal process outgrowth, epithelial seam persistence, and cleft lip. Further investigation revealed that enhanced SHH signaling restricts canonical WNT signaling in the lambdoidal region by promoting expression of genes encoding WNT inhibitors. Moreover, reduction of canonical WNT signaling perturbed p63/interferon regulatory factor 6 (p63/IRF6) signaling, resulting in increased proliferation and decreased cell death, which was followed by persistence of the epithelial seam and cleft lip. Consistent with our results, mutations in genes that disrupt SHH and WNT signaling have been identified in both mice and humans with cleft lip. Collectively, our data illustrate that altered SHH signaling contributes to the etiology and pathogenesis of cleft lip through antagonistic interactions with other gene regulatory networks, including the canonical WNT and p63/IRF6 signaling pathways. PMID:24590292

  11. Wnt signaling, de novo lipogenesis, adipogenesis and ectopic fat.

    Science.gov (United States)

    Song, Kangxing; Wang, Shuxia; Mani, Mitra; Mani, Arya

    2014-11-30

    Wnt signaling is as a major regulator of adipogenesis. It differentially regulates the fate of mesenchymal stem cells (MSC) by promoting osteogenesis and myogenesis, and inhibiting adipogenesis[1]. Its loss of function has been associated with impaired osteogenesis[2] and diverse congenital and adult cardiovascular disorders[3,4]. Our group has identified loss of function mutations in Wnt coreceptor LRP6 that underlie autosomal dominant early onset coronary artery (CAD), osteoporosis and most features of the metabolic syndrome, including high plasma triglyceride and LDL-C, diabetes, hypertension, hyperuricemia and fatty liver disease (unpublished data). Following we will describe our most pertinent findings related to Wnt/LRP6 regulation of de novo lipogenesis and adipogenesis and the role of impaired Wnt signaling in generation of ectopic fat, insulin resistance, elevated plasma lipids and non-alcoholic fatty liver disease (NAFLD).

  12. ASPM regulates Wnt signaling pathway activity in the developing brain.

    Science.gov (United States)

    Buchman, Joshua J; Durak, Omer; Tsai, Li-Huei

    2011-09-15

    Autosomal recessive primary microcephaly (MCPH) is a neural developmental disorder in which patients display significantly reduced brain size. Mutations in Abnormal Spindle Microcephaly (ASPM) are the most common cause of MCPH. Here, we investigate the underlying functions of Aspm in brain development and find that Aspm expression is critical for proper neurogenesis and neuronal migration. The Wnt signaling pathway is known for its roles in embryogenesis, and genome-wide siRNA screens indicate that ASPM is a positive regulator of Wnt signaling. We demonstrate that knockdown of Aspm results in decreased Wnt-mediated transcription, and that expression of stabilized β-catenin can rescue this deficit. Finally, coexpression of stabilized β-catenin can rescue defects observed upon in vivo knockdown of Aspm. Our findings provide an impetus to further explore Aspm's role in facilitating Wnt-mediated neurogenesis programs, which may contribute to psychiatric illness etiology when perturbed.

  13. Wnt co-receptors Lrp5 and Lrp6 differentially mediate Wnt3a signaling in osteoblasts.

    Directory of Open Access Journals (Sweden)

    Aimy Sebastian

    Full Text Available Wnt3a is a major regulator of bone metabolism however, very few of its target genes are known in bone. Wnt3a preferentially signals through transmembrane receptors Frizzled and co-receptors Lrp5/6 to activate the canonical signaling pathway. Previous studies have shown that the canonical Wnt co-receptors Lrp5 and Lrp6 also play an essential role in normal postnatal bone homeostasis, yet, very little is known about specific contributions by these co-receptors in Wnt3a-dependent signaling. We used high-throughput sequencing technology to identify target genes regulated by Wnt3a in osteoblasts and to elucidate the role of Lrp5 and Lrp6 in mediating Wnt3a signaling. Our study identified 782 genes regulated by Wnt3a in primary calvarial osteoblasts. Wnt3a up-regulated the expression of several key regulators of osteoblast proliferation/ early stages of differentiation while inhibiting genes expressed in later stages of osteoblastogenesis. We also found that Lrp6 is the key mediator of Wnt3a signaling in osteoblasts and Lrp5 played a less significant role in mediating Wnt3a signaling.

  14. Wnt and planar cell polarity signaling in cystic renal disease.

    Science.gov (United States)

    Goggolidou, Paraskevi

    2014-01-01

    Cystic kidney diseases can cause end stage renal disease, affecting millions of individuals worldwide. They may arise early or later in life, are characterized by a spectrum of symptoms and can be caused by diverse genetic defects. The primary cilium, a microtubule-based organelle that can serve as a signaling antenna, has been demonstrated to have a significant role in ensuring correct kidney development and function. In the kidney, one of the signaling pathways that requires the cilium for normal development is Wnt signaling. In this review, the roles of primary cilia in relation to canonical and non-canonical Wnt/PCP signaling in cystic renal disease are described. The evidence of the associations between cilia, Wnt signaling and cystic renal disease is discussed and the significance of planar cell polarity-related mechanisms in cystic kidney disease is presented. Although defective Wnt signaling is not the only cause of renal disease, research is increasingly highlighting its importance, encouraging the development of Wnt-associated diagnostic and prognostic tools for cystic renal disease.

  15. Roles of Wnt/{beta}-catenin signaling in epithelial differentiation of mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yajing; Sun, Zhaorui; Qiu, Xuefeng [Immunology and Reproductive Biology Laboratory, Medical College of Nanjing University, Nanjing 210093 (China); Jiangsu Key Laboratory of Molecular Medicine, Nanjing 210093 (China); Li, Yan [Jiangsu Centers for Diseases Prevention and Control, Nanjing 210009 (China); Qin, Jizheng [Immunology and Reproductive Biology Laboratory, Medical College of Nanjing University, Nanjing 210093 (China); Jiangsu Key Laboratory of Molecular Medicine, Nanjing 210093 (China); Han, Xiaodong, E-mail: hanxd@nju.edu.cn [Immunology and Reproductive Biology Laboratory, Medical College of Nanjing University, Nanjing 210093 (China); Jiangsu Key Laboratory of Molecular Medicine, Nanjing 210093 (China)

    2009-12-25

    Bone marrow-derived mesenchymal stem cells (MSCs) have been demonstrated to be able to differentiate into epithelial lineage, but the precise mechanisms controlling this process are unclear. Our aim is to explore the roles of Wnt/{beta}-catenin in the epithelial differentiation of MSCs. Using indirect co-culture of rat MSCs with rat airway epithelial cells (RTE), MSCs expressed several airway epithelial markers (cytokeratin 18, tight junction protein occudin, cystic fibrosis transmembrance regulator). The protein levels of some important members in Wnt/{beta}-catenin signaling were determined, suggested down-regulation of Wnt/{beta}-catenin with epithelial differentiation of MSCs. Furthermore, Wnt3{alpha} can inhibit the epithelial differentiation of MSCs. A loss of {beta}-catenin induced by Dickkopf-1 can enhance MSCs differentiation into epithelial cells. Lithium chloride transiently activated {beta}-catenin expression and subsequently decreased {beta}-catenin level and at last inhibited MSCs to differentiate into airway epithelium. Taken together, our study indicated that RTE cells can trigger epithelial differentiation of MSCs. Blocking Wnt/{beta}-catenin signaling may promote MSCs to differentiate towards airway epithelial cells.

  16. Endocytic Adaptor Protein Tollip Inhibits Canonical Wnt Signaling.

    Directory of Open Access Journals (Sweden)

    Anna Toruń

    Full Text Available Many adaptor proteins involved in endocytic cargo transport exhibit additional functions in other cellular processes which may be either related to or independent from their trafficking roles. The endosomal adaptor protein Tollip is an example of such a multitasking regulator, as it participates in trafficking and endosomal sorting of receptors, but also in interleukin/Toll/NF-κB signaling, bacterial entry, autophagic clearance of protein aggregates and regulation of sumoylation. Here we describe another role of Tollip in intracellular signaling. By performing a targeted RNAi screen of soluble endocytic proteins for their additional functions in canonical Wnt signaling, we identified Tollip as a potential negative regulator of this pathway in human cells. Depletion of Tollip potentiates the activity of β-catenin/TCF-dependent transcriptional reporter, while its overproduction inhibits the reporter activity and expression of Wnt target genes. These effects are independent of dynamin-mediated endocytosis, but require the ubiquitin-binding CUE domain of Tollip. In Wnt-stimulated cells, Tollip counteracts the activation of β-catenin and its nuclear accumulation, without affecting its total levels. Additionally, under conditions of ligand-independent signaling, Tollip inhibits the pathway after the stage of β-catenin stabilization, as observed in human cancer cell lines, characterized by constitutive β-catenin activity. Finally, the regulation of Wnt signaling by Tollip occurs also during early embryonic development of zebrafish. In summary, our data identify a novel function of Tollip in regulating the canonical Wnt pathway which is evolutionarily conserved between fish and humans. Tollip-mediated inhibition of Wnt signaling may contribute not only to embryonic development, but also to carcinogenesis. Mechanistically, Tollip can potentially coordinate multiple cellular pathways of trafficking and signaling, possibly by exploiting its ability to

  17. Wnt signalling and the control of cellular metabolism

    Science.gov (United States)

    Sethi, Jaswinder K.; Vidal-Puig, Antonio

    2015-01-01

    At the cellular level, the biological processes of cell proliferation, growth arrest, differentiation and apoptosis are all tightly coupled to appropriate alterations in metabolic status. In the case of cell proliferation, this requires redirecting metabolic pathways to provide the fuel and basic components for new cells. Ultimately, the successful co-ordination of cell-specific biology with cellular metabolism underscores multicellular processes as diverse as embryonic development, adult tissue remodelling and cancer cell biology. The Wnt signalling network has been implicated in all of these areas. While each of the Wnt-dependent signalling pathways are being individually delineated in a range of experimental systems, our understanding of how they integrate and regulate cellular metabolism is still in its infancy. In the present review we reassess the roles of Wnt signalling in functionally linking cellular metabolism to tissue development and function. PMID:20226003

  18. Wnt signaling through the Ror receptor in the nervous system.

    Science.gov (United States)

    Petrova, Iveta M; Malessy, Martijn J; Verhaagen, Joost; Fradkin, Lee G; Noordermeer, Jasprina N

    2014-02-01

    The receptor tyrosine kinase-like orphan receptor (Ror) proteins are conserved tyrosine kinase receptors that play roles in a variety of cellular processes that pattern tissues and organs during vertebrate and invertebrate development. Ror signaling is required for skeleton and neuronal development and modulates cell migration, cell polarity, and convergent extension. Ror has also been implicated in two human skeletal disorders, brachydactyly type B and Robinow syndrome. Rors are widely expressed during metazoan development including domains in the nervous system. Here, we review recent progress in understanding the roles of the Ror receptors in neuronal migration, axonal pruning, axon guidance, and synaptic plasticity. The processes by which Ror signaling execute these diverse roles are still largely unknown, but they likely converge on cytoskeletal remodeling. In multiple species, Rors have been shown to act as Wnt receptors signaling via novel non-canonical Wnt pathways mediated in some tissues by the adapter protein disheveled and the non-receptor tyrosine kinase Src. Rors can either activate or repress Wnt target expression depending on the cellular context and can also modulate signal transduction by sequestering Wnt ligands away from their signaling receptors. Future challenges include the identification of signaling components of the Ror pathways and bettering our understanding of the roles of these pleiotropic receptors in patterning the nervous system.

  19. TGIF Governs a Feed-Forward Network that Empowers Wnt Signaling to Drive Mammary Tumorigenesis

    OpenAIRE

    Zhang, Ming-Zhu; Ferrigno, Olivier; Wang, Zhe; Ohnishi, Mutsuko; Prunier, Céline; Levy, Laurence; Razzaque, Mohammed; Horne, Williams C.; Romero, Damian; Tzivion, Guri; Colland, Frédéric; Baron, Roland; Atfi, Azeddine

    2015-01-01

    Many types of human cancers having hyperactivated Wnt signaling display no causative alterations in known effectors of this pathway. Here, we report a function of TGIF in Wnt signaling. TGIF associates with and diverts Axin1 and Axin2 from the β-Catenin destruction complex therefore allowing β-Catenin accrual. Intriguingly, activation of Wnt signaling induces the expression of TGIF, which unveils a feed-forward loop that ensures effective integration of Wnt signaling. In triple negative breas...

  20. Distinctive Roles of Canonical and Noncanonical Wnt Signaling in Human Embryonic Cardiomyocyte Development

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    Silvia Mazzotta

    2016-10-01

    Full Text Available Wnt signaling is a key regulator of vertebrate heart development; however, specific roles for human cardiomyocyte development remain uncertain. Here we use human embryonic stem cells (hESCs to analyze systematically in human cardiomyocyte development the expression of endogenous Wnt signaling components, monitor pathway activity, and dissect stage-specific requirements for canonical and noncanonical Wnt signaling mechanisms using small-molecule inhibitors. Our analysis suggests that WNT3 and WNT8A, via FZD7 and canonical signaling, regulate BRACHYURY expression and mesoderm induction; that WNT5A/5B, via ROR2 and noncanonical signaling, regulate MESP1 expression and cardiovascular development; and that later in development WNT2, WNT5A/5B, and WNT11, via FZD4 and FZD6, regulate functional cardiomyocyte differentiation via noncanonical Wnt signaling. Our findings confirm in human development previously proposed roles for canonical Wnt signaling in sequential stages of vertebrate cardiomyogenesis, and identify more precise roles for noncanonical signaling and for individual Wnt signal and Wnt receptor genes in human cardiomyocyte development.

  1. Primary cilia integrate hedgehog and Wnt signaling during tooth development.

    Science.gov (United States)

    Liu, B; Chen, S; Cheng, D; Jing, W; Helms, J A

    2014-05-01

    Many ciliopathies have clinical features that include tooth malformations but how these defects come about is not clear. Here we show that genetic deletion of the motor protein Kif3a in dental mesenchyme results in an arrest in odontogenesis. Incisors are completely missing, and molars are enlarged in Wnt1(Cre+)Kif3a(fl/fl) embryos. Although amelogenesis and dentinogenesis initiate in the molar tooth bud, both processes terminate prematurely. We demonstrate that loss of Kif3a in dental mesenchyme results in loss of Hedgehog signaling and gain of Wnt signaling in this same tissue. The defective dental mesenchyme then aberrantly signals to the dental epithelia, which prompts an up-regulation in the Hedgehog and Wnt responses in the epithelia and leads to multiple attempts at invagination and an expanded enamel organ. Thus, the primary cilium integrates Hedgehog and Wnt signaling between dental epithelia and mesenchyme, and this cilia-dependent integration is required for proper tooth development.

  2. Delamination of neural crest cells requires transient and reversible Wnt inhibition mediated by Dact1/2.

    Science.gov (United States)

    Rabadán, M Angeles; Herrera, Antonio; Fanlo, Lucia; Usieto, Susana; Carmona-Fontaine, Carlos; Barriga, Elias H; Mayor, Roberto; Pons, Sebastián; Martí, Elisa

    2016-06-15

    Delamination of neural crest (NC) cells is a bona fide physiological model of epithelial-to-mesenchymal transition (EMT), a process that is influenced by Wnt/β-catenin signalling. Using two in vivo models, we show that Wnt/β-catenin signalling is transiently inhibited at the time of NC delamination. In attempting to define the mechanism underlying this inhibition, we found that the scaffold proteins Dact1 and Dact2, which are expressed in pre-migratory NC cells, are required for NC delamination in Xenopus and chick embryos, whereas they do not affect the motile properties of migratory NC cells. Dact1/2 inhibit Wnt/β-catenin signalling upstream of the transcriptional activity of T cell factor (TCF), which is required for EMT to proceed. Dact1/2 regulate the subcellular distribution of β-catenin, preventing β-catenin from acting as a transcriptional co-activator to TCF, yet without affecting its stability. Together, these data identify a novel yet important regulatory element that inhibits β-catenin signalling, which then affects NC delamination. © 2016. Published by The Company of Biologists Ltd.

  3. Advancement of Wnt signal pathway and the target of breast cancer

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    Liang Quan

    2016-01-01

    Full Text Available Wnt/β-catenin signaling has been proved to play an important role in the development and promotion of cancer metastasis. The activation of Wnt signals can lead to duplicating, updating, metastasizing and relapsing. The Wnt signaling pathway is mainly divided into the Wnt/β-catenin pathway and the Wnt/calcium pathway. A better understanding of all the diverse functions of Wnt and their molecular mechanisms has evoked prevailing interest in identifying additional targets related to the Wnt /β-catenin pathways in breast cancer. A number of new target, related to Wnt /β-catenin pathways have been identified in recent years, including NOP14, BKCa channels, Emilin2, WISP, MicroRNAs, NRBP1, TRAF4, and Wntless. In this review, we will introduce the new targets related to the Wnt /β-catenin pathways in breast cancer.

  4. Expression profiling of Wnt signaling genes during gonadal differentiation and gametogenesis in rainbow trout.

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    Nicol, B; Guiguen, Yann

    2011-01-01

    Wnt signaling plays major roles in various processes, including ovarian differentiation and development in mammals. In order to explore its potential implication during gonadal development in a nonmammalian vertebrate species, expression of Wnt signaling genes was investigated in rainbow trout during gonadal differentiation and gametogenesis. Multiple Wnt pathway genes were expressed and exhibited distinct expression patterns. In ovary, tcf7 was highly expressed during early differentiation, whereas no sexually dimorphic expression of rspo1 was detected. During later ovarian development, wnt11 was highly expressed in granulosa cells and oocytes suggesting an implication in folliculogenesis and oogenesis, whereas wnt9b was principally detected in granulosa cells. In testis, Wnt pathway genes were mostly expressed during early spermatogenesis. Overall, these present results suggest that Wnt signaling is implicated in multiple processes of male and female gonadal development and provide basis for future studies on Wnt signaling functions in teleost fish gonads. Copyright © 2011 S. Karger AG, Basel.

  5. PR130 is a modulator of the Wnt-signaling cascade that counters repression of the antagonist Naked cuticle

    NARCIS (Netherlands)

    Creyghton, M.P.; Roël, G.; Eichhorn, P.J.A.; Vredeveld, L.C.; Destrée, O.; Bernards, R.A.

    2006-01-01

    The Wnt-signaling cascade is required for several crucial steps during early embryogenesis, and its activity is modulated by various agonists and antagonists to provide spatiotemporal-specific signaling. Naked cuticle is a Wnt antagonist that itself is induced by Wnt signaling to keep Wnt signaling

  6. Both canonical and non-canonical Wnt signaling independently promote stem cell growth in mammospheres.

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    Alexander M Many

    Full Text Available The characterization of mammary stem cells, and signals that regulate their behavior, is of central importance in understanding developmental changes in the mammary gland and possibly for targeting stem-like cells in breast cancer. The canonical Wnt/β-catenin pathway is a signaling mechanism associated with maintenance of self-renewing stem cells in many tissues, including mammary epithelium, and can be oncogenic when deregulated. Wnt1 and Wnt3a are examples of ligands that activate the canonical pathway. Other Wnt ligands, such as Wnt5a, typically signal via non-canonical, β-catenin-independent, pathways that in some cases can antagonize canonical signaling. Since the role of non-canonical Wnt signaling in stem cell regulation is not well characterized, we set out to investigate this using mammosphere formation assays that reflect and quantify stem cell properties. Ex vivo mammosphere cultures were established from both wild-type and Wnt1 transgenic mice and were analyzed in response to manipulation of both canonical and non-canonical Wnt signaling. An increased level of mammosphere formation was observed in cultures derived from MMTV-Wnt1 versus wild-type animals, and this was blocked by treatment with Dkk1, a selective inhibitor of canonical Wnt signaling. Consistent with this, we found that a single dose of recombinant Wnt3a was sufficient to increase mammosphere formation in wild-type cultures. Surprisingly, we found that Wnt5a also increased mammosphere formation in these assays. We confirmed that this was not caused by an increase in canonical Wnt/β-catenin signaling but was instead mediated by non-canonical Wnt signals requiring the receptor tyrosine kinase Ror2 and activity of the Jun N-terminal kinase, JNK. We conclude that both canonical and non-canonical Wnt signals have positive effects promoting stem cell activity in mammosphere assays and that they do so via independent signaling mechanisms.

  7. LGR4 and LGR5 are R-spondin receptors mediating Wnt/β-catenin and Wnt/PCP signalling

    Science.gov (United States)

    Glinka, Andrei; Dolde, Christine; Kirsch, Nadine; Huang, Ya-Lin; Kazanskaya, Olga; Ingelfinger, Dierk; Boutros, Michael; Cruciat, Cristina-Maria; Niehrs, Christof

    2011-01-01

    R-spondins are secreted Wnt signalling agonists, which regulate embryonic patterning and stem cell proliferation, but whose mechanism of action is poorly understood. Here we show that R-spondins bind to the orphan G-protein-coupled receptors LGR4 and LGR5 by their Furin domains. Gain- and loss-of-function experiments in mammalian cells and Xenopus embryos indicate that LGR4 and LGR5 promote R-spondin-mediated Wnt/β-catenin and Wnt/PCP signalling. R-spondin-triggered β-catenin signalling requires Clathrin, while Wnt3a-mediated β-catenin signalling requires Caveolin-mediated endocytosis, suggesting that internalization has a mechanistic role in R-spondin signalling. PMID:21909076

  8. Wnt signaling in form deprivation myopia of the mice retina.

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    Mingming Ma

    Full Text Available BACKGROUND: The canonical Wnt signaling pathway plays important roles in cellular proliferation and differentiation, axonal outgrowth, cellular maintenance in retinas. Here we test the hypothesis that elements of the Wnt signaling pathway are involved in the regulation of eye growth and prevention of myopia, in the mouse form-deprivation myopia model. METHODOLOGY/PRINCIPAL FINDINGS: (1 One hundred twenty-five C57BL/6 mice were randomly distributed into form-deprivation myopia and control groups. Form-deprivation myopia (FDM was induced by suturing the right eyelid, while the control group received no treatment. After 1, 2, and 4 weeks of treatment, eyes were assessed in vivo by cycloplegic retinoscopic refraction and axial length measurement by photography or A-scan ultrasonography. Levels of retinal Wnt2b, Fzd5 and β-catenin mRNA and protein were evaluated using RT-PCR and western blotting, respectively. (2 Another 96 mice were divided into three groups: control, drugs-only, and drugs+FDM (by diffuser. Experimentally treated eyes in the last two groups received intravitreal injections of vehicle or the proteins, DKK-1 (Wnt-pathway antagonist or Norrin (Wnt-pathway agonist, once every three days, for 4 injections total. Axial length and retinoscopic refraction were measured on the 14th day of form deprivation. Following form-deprivation for 1, 2, and 4 weeks, FDM eyes had a relatively myopic refractive error, compared with contralateral eyes. There were no significant differences in refractive error between right and left eye in control group. The amounts of Wnt2b, Fzd5 and β-catenin mRNA and protein were significantly greater in form-deprived myopia eyes than in control eyes.DKK-1 (antagonist reduced the myopic shift in refractive error and increase in axial elongation, whereas Norrin had the opposite effect in FDM eyes. CONCLUSIONS/SIGNIFICANCE: Our studies provide the first evidence that the Wnt2b signaling pathway may play a role in the

  9. TGIF Governs a Feed-Forward Network That Empowers Wnt Signaling to Drive Mammary Tumorigenesis

    Science.gov (United States)

    Zhang, Ming-Zhu; Ferrigno, Olivier; Wang, Zhe; Ohnishi, Mutsuko; Prunier, Céline; Levy, Laurence; Razzaque, Mohammed; Horne, Williams C.; Romero, Damian; Tzivion, Guri; Colland, Frédéric; Baron, Roland; Atfi, Azeddine

    2015-01-01

    SUMMARY Many types of human cancers having hyperactivated Wnt signaling display no causative alterations in known effectors of this pathway. Here, we report a function of TGIF in Wnt signaling. TGIF associates with and diverts Axin1 and Axin2 from the β-Catenin destruction complex therefore allowing β-Catenin accrual. Intriguingly, activation of Wnt signaling induces the expression of TGIF, which unveils a feed-forward loop that ensures effective integration of Wnt signaling. In triple negative breast cancers (TNBC), elevated levels of TGIF correlate with high Wnt signaling and poor survival of patients. Moreover, genetic experiments revealed that Tgif1 ablation impeded mammary tumor development in MMTV-Wnt1 mice, further underscoring a requirement of TGIF for oncogenic Wnt signaling. PMID:25873176

  10. Wnt signaling-mediated redox regulation maintains the germ line stem cell differentiation niche.

    Science.gov (United States)

    Wang, Su; Gao, Yuan; Song, Xiaoqing; Ma, Xing; Zhu, Xiujuan; Mao, Ying; Yang, Zhihao; Ni, Jianquan; Li, Hua; Malanowski, Kathryn E; Anoja, Perera; Park, Jungeun; Haug, Jeff; Xie, Ting

    2015-10-09

    Adult stem cells continuously undergo self-renewal and generate differentiated cells. In the Drosophila ovary, two separate niches control germ line stem cell (GSC) self-renewal and differentiation processes. Compared to the self-renewing niche, relatively little is known about the maintenance and function of the differentiation niche. In this study, we show that the cellular redox state regulated by Wnt signaling is critical for the maintenance and function of the differentiation niche to promote GSC progeny differentiation. Defective Wnt signaling causes the loss of the differentiation niche and the upregulated BMP signaling in differentiated GSC progeny, thereby disrupting germ cell differentiation. Mechanistically, Wnt signaling controls the expression of multiple glutathione-S-transferase family genes and the cellular redox state. Finally, Wnt2 and Wnt4 function redundantly to maintain active Wnt signaling in the differentiation niche. Therefore, this study has revealed a novel strategy for Wnt signaling in regulating the cellular redox state and maintaining the differentiation niche.

  11. Wnt3a Promotes the Vasculogenic Mimicry Formation of Colon Cancer via Wnt/β-Catenin Signaling.

    Science.gov (United States)

    Qi, Lisha; Song, Wangzhao; Liu, Zhiyong; Zhao, Xiulan; Cao, Wenfeng; Sun, Baocun

    2015-08-10

    Our previous study provided evidence that non-canonical Wnt signaling is involved in regulating vasculogenic mimicry (VM) formation. However, the functions of canonical Wnt signaling in VM formation have not yet been explored. In this study, we found the presence of VM was related to colon cancer histological differentiation (p colon cancer samples showed increased Wnt3a expression (p colon cancer cells promoted the capacity to form tube-like structures in the three-dimensional (3-D) culture together with increased expression of endothelial phenotype-associated proteins such as VEGFR2 and VE-cadherin. The mouse xenograft model showed that Wnt3a-overexpressing cells grew into larger tumor masses and formed more VM than the control cells. In addition, the Wnt/β-catenin signaling antagonist Dickkopf-1(Dkk1) can reverse the capacity to form tube-like structures and can decrease the expressions of VEGFR2 and VE-cadherin in Wnt3a-overexpressing cells. Taken together, our results suggest that Wnt/β-catenin signaling is involved in VM formation in colon cancer and might contribute to the development of more accurate treatment modalities aimed at VM.

  12. Aberrant Wnt/β-Catenin Signaling in Pancreatic Adenocarcinoma

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    Gang Zeng

    2006-04-01

    Full Text Available Wnt/β-catenin signaling plays an important role in normal development. However, its aberrant activation is associated with several cancers. The aim of this study is to examine the Wnt/β-catenin pathway in patients with advanced pancreatic adenocarcinoma (n = 31. Paraffin sections from tumors (n = 16 and normal pancreata (n = 3 were used to determine the localization of β-catenin. An additional 15 frozen tumors, adjacent normal pancreata (n = 5, or normal pancreata (n = 4 were utilized for protein isolation. Tumors were also examined for mutations in exon 3 of the CTNNB1 gene. More than 65% of the tumors showed an increase in total β-catenin, consistent with its enhanced membranous, cytoplasmic, and nuclear localization, but only two showed mutations in CTNNB1. The majority of the remaining tumors demonstrated concurrent increases in Wnt-1 and frizzled-2 (positive regulators and a decrease in Ser45/Thr41-phospho-β-catenin. Electrophoretic mobility shift assay demonstrated β-cateninT-cell factor binding in tumors only. Adenomatous polyposis coli and axin, which are both negative regulators, remained unchanged. Unexpectedly, total glycogen synthase kinase-3β protein was elevated in these tumors. Elevated levels of E-cadherin were also observed, although E-cadherin-β-catenin association in tumors remained unaffected. Thus, Wnt/β-catenin activation was observed in 65% of pancreatic adenocarcinomas, independently of β-catenin gene mutations in most tumors.

  13. Wnt signaling and colon tumorigenesis - A view from the periphery

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    Burgess, Antony W., E-mail: burgess@ludwig.edu.au [Parkville Branch, Ludwig Institute for Cancer Research, Melbourne, 3050 (Australia); Faux, Maree C. [Parkville Branch, Ludwig Institute for Cancer Research, Melbourne, 3050 (Australia); Layton, Meredith J. [Department of Biochemistry and Molecular Biology, Monash University, Melbourne, 3800 (Australia); Ramsay, Robert G. [Peter MacCallum Cancer Centre, Melbourne, 3002 (Australia); Pathology Department, the University of Melbourne, Parkville, 3050 (Australia)

    2011-11-15

    In this brief overview we discuss the association between Wnt signaling and colon cell biology and tumorigenesis. Our current understanding of the role of Apc in the {beta}-catenin destruction complex is compared with potential roles for Apc in cell adhesion and migration. The requirement for phosphorylation in the proteasomal-mediated degradation of {beta}-catenin is contrasted with roles for phospho-{beta}-catenin in the activation of transcription, cell adhesion and migration. The synergy between Myb and {beta}-catenin regulation of transcription in crypt stem cells during Wnt signaling is discussed. Finally, potential effects of growth factor regulatory systems, Apc or truncated-Apc on crypt morphogenesis, stem cell localization and crypt fission are considered.

  14. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

    Science.gov (United States)

    Li, Xiao; Florez, Sergio; Wang, Jianbo; Cao, Huojun; Amendt, Brad A

    2013-01-01

    Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  15. Dact2 represses PITX2 transcriptional activation and cell proliferation through Wnt/beta-catenin signaling during odontogenesis.

    Directory of Open Access Journals (Sweden)

    Xiao Li

    Full Text Available Dact proteins belong to the Dapper/Frodo protein family and function as cytoplasmic attenuators in Wnt and TGFβ signaling. Previous studies show that Dact1 is a potent Wnt signaling inhibitor by promoting degradation of β-catenin. We report a new mechanism for Dact2 function as an inhibitor of the canonical Wnt signaling pathway by interacting with PITX2. PITX2 is a downstream transcription factor in Wnt/β-catenin signaling, and PITX2 synergizes with Lef-1 to activate downstream genes. Immunohistochemistry verified the expression of Dact2 in the tooth epithelium, which correlated with Pitx2 epithelial expression. Dact2 loss of function and PITX2 gain of function studies reveal a feedback mechanism for controlling Dact2 expression. Pitx2 endogenously activates Dact2 expression and Dact2 feeds back to repress Pitx2 transcriptional activity. A Topflash reporter system was employed showing PITX2 activation of Wnt signaling, which is attenuated by Dact2. Transient transfections demonstrate the inhibitory effect of Dact2 on critical dental epithelial differentiation factors during tooth development. Dact2 significantly inhibits PITX2 activation of the Dlx2 and amelogenin promoters. Multiple lines of evidence conclude the inhibition is achieved by the physical interaction between Dact2 and Pitx2 proteins. The loss of function of Dact2 also reveals increased cell proliferation due to up-regulated Wnt downstream genes, cyclinD1 and cyclinD2. In summary, we have identified a novel role for Dact2 as an inhibitor of the canonical Wnt pathway in embryonic tooth development through its regulation of cell proliferation and differentiation.

  16. Wnt/β-Catenin Signaling Regulates Proliferation of Human Cornea Epithelial Stem/Progenitor Cells

    Science.gov (United States)

    Nakatsu, Martin N.; Ding, Zhenhua; Ng, Madelena Y.; Truong, Thuy T.; Yu, Fei

    2011-01-01

    Purpose. To investigate the expression and role of the Wnt signaling pathway in human limbal stem cells (LSCs). Methods. Total RNA was isolated from the human limbus and central cornea. Limbal or cornea-specific transcripts were identified through quantitative real-time PCR. Protein expression of Wnt molecules was confirmed by immunohistochemistry on human ocular tissue. Activation of Wnt signaling using lithium chloride was achieved in vitro and its effects on LSC differentiation and proliferation were evaluated. Results. Expression of Wnt2, Wnt6, Wnt11, Wnt16b, and four Wnt inhibitors were specific to the limbal region, whereas Wnt3, Wnt7a, Wnt7b, and Wnt10a were upregulated in the central cornea. Nuclear localization of β-catenin was observed in a very small subset of basal epithelial cells only at the limbus. Activation of Wnt/β-catenin signaling increased the proliferation and colony-forming efficiency of primary human LSCs. The stem cell phenotype was maintained, as shown by higher expression levels of putative corneal epithelial stem cell markers, ATP-binding cassette family G2 and ΔNp63α, and low expression levels of mature cornea epithelial cell marker, cytokeratin 12. Conclusions. These findings demonstrate for the first time that Wnt signaling is present in the ocular surface epithelium and plays an important role in the regulation of LSC proliferation. Modulation of Wnt signaling could be of clinical application to increase the efficiency of ex vivo expansion of corneal epithelial stem/progenitor cells for transplantation. PMID:21357396

  17. Metastases and Colon Cancer Tumor Growth Display Divergent Responses to Modulation of Canonical WNT Signaling.

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    Chandan Seth

    Full Text Available Human colon cancers commonly harbor loss of function mutations in APC, a repressor of the canonical WNT pathway, thus leading to hyperactive WNT-TCF signaling. Re-establishment of Apc function in mice, engineered to conditionally repress Apc through RNAi, resolve the intestinal tumors formed due to hyperactivated Wnt-Tcf signaling. These and other results have prompted the search for specific WNT pathway antagonists as therapeutics for clinically problematic human colon cancers and associated metastases, which remain largely incurable. This widely accepted view seems at odds with a number of findings using patient-derived material: Canonical TCF targets are repressed, instead of being hyperactivated, in advanced colon cancers, and repression of TCF function does not generally result in tumor regression in xenografts. The results of a number of genetic mouse studies have also suggested that canonical WNT-TCF signaling drives metastases, but direct in vivo tests are lacking, and, surprisingly, TCF repression can enhance directly seeded metastatic growth. Here we have addressed the abilities of enhanced and blocked WNT-TCF signaling to alter tumor growth and distant metastases using xenografts of advanced human colon cancers in mice. We find that endogenous WNT-TCF signaling is mostly anti-metastatic since downregulation of TCF function with dnTCF generally enhances metastatic spread. Consistently, elevating the level of WNT signaling, by increasing the levels of WNT ligands, is not generally pro-metastatic. Our present and previous data reveal a heterogeneous response to modulating WNT-TCF signaling in human cancer cells. Nevertheless, the findings that a fraction of colon cancers tested require WNT-TCF signaling for tumor growth but all respond to repressed signaling by increasing metastases beg for a reevaluation of the goal of blocking WNT-TCF signaling to universally treat colon cancers. Our data suggest that WNT-TCF blockade may be effective

  18. Wnt/β-Catenin Signaling Pathway in Skin Carcinogenesis and Therapy

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    Jing Li

    2015-01-01

    Full Text Available Cooperating with other signaling pathways, Wnt signaling controls cell proliferation, morphology, motility, and embryonic development destination and maintains the homeostasis of tissues including skin, blood, intestine, and brain by regulating somatic stem cells and their niches throughout adult life. Abnormal regulation of Wnt pathways leads to neoplastic proliferation in these tissues. Recent research shows that Wnt signaling is also associated with the regulation of cancer stem cells (CSCs through a similar mechanism to that observed in normal adult stem cells. Thus, the Wnt/β-catenin signaling pathway has been intensively studied and characterized. For this review, we will focus on the regulation of the Wnt/β-catenin signaling pathway in skin cancer. With the important role in stemness and skin CSC proliferation, the Wnt/β-catenin signaling pathway and its elements have the potential to be targets for skin cancer therapy.

  19. NUMB is a break of WNT-Notch signaling cycle.

    Science.gov (United States)

    Katoh, Masuko; Katoh, Masaru

    2006-09-01

    Notch, FGF and WNT signaling pathways cross-talk during embryogenesis, tissue regeneration and carcinogenesis. Notch-ligand binding to Notch receptors leads to the cleavage of Notch receptors and the following nuclear translocation of Notch intracellular domain (NICD) to induce transcriptional activation of Notch target genes. Notch signaling inhibitors, NUMB and NUMB-like (NUMBL), are docking proteins with PTB domain. We searched for the TCF/LEF-binding site within the promoter region of NUMB and NUMBL genes. Because two TCF/LEF-binding sites were identified within human NUMB promoter based on bioinformatics and human intelligence (Humint), comparative integromics analyses on NUMB orthologs were further performed. Chimpanzee NUBM gene, consisting of 13 exons, was identified within NW_115880.1 genome sequence. XM_510045.1 was not the correct coding sequence for chimpanzee NUMB. Chimpanzee NUMB gene was found to encode a 651-amino-acid protein showing 99.5, 93.9 and 82.6% total-amino-acid identity with human NUMB, mouse Numb and chicken numb, respectively. Human NUMB mRNA was expressed in placenta, ES cells, neural tissues, trachea, testis, uterus, thymus, coronary artery as well as in a variety of tumors, such as cervical cancer, tong tumor, brain tumor, colorectal and breast cancer. Although distal TCF/LEF-binding site within human NUMB promoter was conserved only among primate NUMB orthologs, proximal TCF/LEF-binding site was conserved among primate and rodent NUMB orthologs. NUMB, JAG1, FGF18, FGF20 and SPRY4 are potent targets of the canonical WNT signaling pathway in progenitor cells. NUMB inhibits Notch signaling in progenitor cells to induce differentiation, while JAG1 activates Notch signaling in stem cells to maintain self-renewal potential. Because Notch signaling inhibitor NUMB was identified as the safe apparatus for the WNT - Notch signaling cycle, epigenetic silencing, deletion and loss-of-function mutation of NUMB gene could lead to carcinogenesis

  20. Dual Function of Wnt Signaling during Neuronal Differentiation of Mouse Embryonic Stem Cells

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    Hanjun Kim

    2015-01-01

    Full Text Available Activation of Wnt signaling enhances self-renewal of mouse embryonic and neural stem/progenitor cells. In contrast, undifferentiated ES cells show a very low level of endogenous Wnt signaling, and ectopic activation of Wnt signaling has been shown to block neuronal differentiation. Therefore, it remains unclear whether or not endogenous Wnt/β-catenin signaling is necessary for self-renewal or neuronal differentiation of ES cells. To investigate this, we examined the expression profiles of Wnt signaling components. Expression levels of Wnts known to induce β-catenin were very low in undifferentiated ES cells. Stable ES cell lines which can monitor endogenous activity of Wnt/β-catenin signaling suggest that Wnt signaling was very low in undifferentiated ES cells, whereas it increased during embryonic body formation or neuronal differentiation. Interestingly, application of small molecules which can positively (BIO, GSK3β inhibitor or negatively (IWR-1-endo, Axin stabilizer control Wnt/β-catenin signaling suggests that activation of that signaling at different time periods had differential effects on neuronal differentiation of 46C ES cells. Further, ChIP analysis suggested that β-catenin/TCF1 complex directly regulated the expression of Sox1 during neuronal differentiation. Overall, our data suggest that Wnt/β-catenin signaling plays differential roles at different time points of neuronal differentiation.

  1. WNT4 mediates estrogen receptor signaling and endocrine resistance in invasive lobular carcinoma cell lines.

    Science.gov (United States)

    Sikora, Matthew J; Jacobsen, Britta M; Levine, Kevin; Chen, Jian; Davidson, Nancy E; Lee, Adrian V; Alexander, Caroline M; Oesterreich, Steffi

    2016-09-20

    Invasive lobular carcinoma (ILC) of the breast typically presents with clinical biomarkers consistent with a favorable response to endocrine therapies, and over 90 % of ILC cases express the estrogen receptor (ER). However, a subset of ILC cases may be resistant to endocrine therapies, suggesting that ER biology is unique in ILC. Using ILC cell lines, we previously demonstrated that ER regulates a distinct gene expression program in ILC cells, and we hypothesized that these ER-driven pathways modulate the endocrine response in ILC. One potential novel pathway is via the Wnt ligand WNT4, a critical signaling molecule in mammary gland development regulated by the progesterone receptor. The ILC cell lines MDA-MB-134-VI, SUM44PE, and BCK4 were used to assess WNT4 gene expression and regulation, as well as the role of WNT4 in estrogen-regulated proliferation. To assess these mechanisms in the context of endocrine resistance, we developed novel ILC endocrine-resistant long-term estrogen-deprived (ILC-LTED) models. ILC and ILC-LTED cell lines were used to identify upstream regulators and downstream signaling effectors of WNT4 signaling. ILC cells co-opted WNT4 signaling by placing it under direct ER control. We observed that ER regulation of WNT4 correlated with use of an ER binding site at the WNT4 locus, specifically in ILC cells. Further, WNT4 was required for endocrine response in ILC cells, as WNT4 knockdown blocked estrogen-induced proliferation. ILC-LTED cells remained dependent on WNT4 for proliferation, by either maintaining ER function and WNT4 regulation or uncoupling WNT4 from ER and upregulating WNT4 expression. In the latter case, WNT4 expression was driven by activated nuclear factor kappa-B signaling in ILC-LTED cells. In ILC and ILC-LTED cells, WNT4 led to suppression of CDKN1A/p21, which is critical for ILC cell proliferation. CDKN1A knockdown partially reversed the effects of WNT4 knockdown. WNT4 drives a novel signaling pathway in ILC cells, with a

  2. PAF and EZH2 induce Wnt/β-catenin signaling hyperactivation.

    Science.gov (United States)

    Jung, Hae-Yun; Jun, Sohee; Lee, Moonsup; Kim, Han-Cheon; Wang, Xin; Ji, Hong; McCrea, Pierre D; Park, Jae-Il

    2013-10-24

    Fine control of Wnt signaling is essential for various cellular and developmental decision-making processes. However, deregulation of Wnt signaling leads to pathological consequences, one of which is cancer. Here, we identify a function of PAF, a component of translesion DNA synthesis, in modulating Wnt signaling. PAF is specifically overexpressed in colon cancer cells and intestinal stem cells and is required for colon cancer cell proliferation. In Xenopus laevis, ventrovegetal expression of PAF hyperactivates Wnt signaling, developing a secondary axis with β-catenin target gene upregulation. Upon Wnt signaling activation, PAF dissociates from PCNA and binds directly to β-catenin. Then, PAF recruits EZH2 to the β-catenin transcriptional complex and specifically enhances Wnt target gene transactivation, independently of EZH2's methyltransferase activity. In mice, conditional expression of PAF induces intestinal neoplasia via Wnt signaling hyperactivation. Our studies reveal an unexpected role of PAF in regulating Wnt signaling and propose a regulatory mechanism of Wnt signaling during tumorigenesis. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Regulation of epithelial branching morphogenesis and cancer cell growth of the prostate by Wnt signaling.

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    Bu-Er Wang

    Full Text Available Although Wnt signaling has been shown to be important for embryonic morphogenesis and cancer pathogenesis of several tissues, its role in prostatic development and tumorigenesis is not well understood. Here we show that Wnt signaling regulated prostatic epithelial branching morphogenesis and luminal epithelial cell differentiation in developing rat prostate organ cultures. Specifically, Wnt signaling regulated the proliferation of prostate epithelial progenitor cells. Assessment of the expression levels of a Wnt pathway transcriptional target gene, Axin2, showed that the Wnt pathway was activated in the developing prostate, but was down-regulated in the adult. Castration resulted in an upregulation of Axin2 whereas androgen replacement resulted in a down regulation of Axin2. Such dynamic changes of Wnt activity was also confirmed in a BAT-gal transgenic mouse line in which beta-galactosidase reporter is expressed under the control of beta-catenin/T cell factor responsive elements. Furthermore, we evaluated the role of Wnt signaling in prostate tumorigenesis. Axin2 expression was found upregulated in the majority of human prostate cancer cell lines examined. Moreover, addition of a Wnt pathway inhibitor, Dickkopf 1 (DKK1, into the culture medium significantly inhibited prostate cancer cell growth and migration. These findings suggest that Wnt signaling regulates prostatic epithelial ductal branching morphogenesis by influencing cell proliferation, and highlights a role for Wnt pathway activation in prostatic cancer progression.

  4. Genomic insights into Wnt signaling in an early diverging metazoan, the ctenophore Mnemiopsis leidyi

    Science.gov (United States)

    2010-01-01

    Background Intercellular signaling pathways are a fundamental component of the integrating cellular behavior required for the evolution of multicellularity. The genomes of three of the four early branching animal phyla (Cnidaria, Placozoa and Porifera) have been surveyed for key components, but not the fourth (Ctenophora). Genomic data from ctenophores could be particularly relevant, as ctenophores have been proposed to be one of the earliest branching metazoan phyla. Results A preliminary assembly of the lobate ctenophore Mnemiopsis leidyi genome generated using next-generation sequencing technologies were searched for components of a developmentally important signaling pathway, the Wnt/β-catenin pathway. Molecular phylogenetic analysis shows four distinct Wnt ligands (MlWnt6, MlWnt9, MlWntA and MlWntX), and most, but not all components of the receptor and intracellular signaling pathway were detected. In situ hybridization of the four Wnt ligands showed that they are expressed in discrete regions associated with the aboral pole, tentacle apparati and apical organ. Conclusions Ctenophores show a minimal (but not obviously simple) complement of Wnt signaling components. Furthermore, it is difficult to compare the Mnemiopsis Wnt expression patterns with those of other metazoans. mRNA expression of Wnt pathway components appears later in development than expected, and zygotic gene expression does not appear to play a role in early axis specification. Notably absent in the Mnemiopsis genome are most major secreted antagonists, which suggests that complex regulation of this secreted signaling pathway probably evolved later in animal evolution. PMID:20920349

  5. Sall1-dependent signals affect Wnt signaling and ureter tip fate to initiate kidney development

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    Kiefer, Susan M.; Robbins, Lynn; Stumpff, Kelly M.; Lin, Congxing; Ma, Liang; Rauchman, Michael

    2010-01-01

    Development of the metanephric kidney depends on precise control of branching of the ureteric bud. Branching events represent terminal bifurcations that are thought to depend on unique patterns of gene expression in the tip compared with the stalk and are influenced by mesenchymal signals. The metanephric mesenchyme-derived signals that control gene expression at the ureteric bud tip are not well understood. In mouse Sall1 mutants, the ureteric bud grows out and invades the metanephric mesenchyme, but it fails to initiate branching despite tip-specific expression of Ret and Wnt11. The stalk-specific marker Wnt9b and the β-catenin downstream target Axin2 are ectopically expressed in the mutant ureteric bud tips, suggesting that upregulated canonical Wnt signaling disrupts ureter branching in this mutant. In support of this hypothesis, ureter arrest is rescued by lowering β-catenin levels in the Sall1 mutant and is phenocopied by ectopic expression of a stabilized β-catenin in the ureteric bud. Furthermore, transgenic overexpression of Wnt9b in the ureteric bud causes reduced branching in multiple founder lines. These studies indicate that Sall1-dependent signals from the metanephric mesenchyme are required to modulate ureteric bud tip Wnt patterning in order to initiate branching. PMID:20702564

  6. [Cytokines in bone diseases. Wnt signaling and osteoporosis-pseudoglioma syndrome].

    Science.gov (United States)

    Ozono, Keiichi

    2010-10-01

    Wnt signaling system plays essential roles in development, cancer and bone metabolism. Canonical wnt signaling, which involves wnt ligands, receptor named frizzled and co-receptors LRP5/6, beta-catenin and transcription factors named LEF/TCF is well characterized and its defect causes bone abnormalities. The loss-of-function type of the LRP5 gene mutation is responsible for osteoporosis-pseudoglioma syndrome. In addition, the LRP6 gene mutation leads to osteoporosis and metabolic syndrome. Thus, wnt signaling system is one of determinant factors for bone mineral density.

  7. Involvement of wnt signaling pathways in the metamorphosis of the bryozoan bugula neritina

    KAUST Repository

    Wong, Yue Him

    2012-03-20

    In this study, we analyzed the metamorphosis of the marine bryozoan Bugula neritina. We observed the morphogenesis of the ancestrula. We defined three distinct pre-ancestrula stages based on the anatomy of the developing polypide and the overall morphology of pre-ancestrula. We then used an annotation based enrichment analysis tool to analyze the B. neritina transcriptome and identified over-representation of genes related to Wnt signaling pathways, suggesting its involvement in metamorphosis. Finally, we studied the temporal-spatial gene expression studies of several Wnt pathway genes. We found that one of the Wnt ligand, BnWnt10, was expressed spatially opposite to the Wnt antagonist BnsFRP within the blastemas, which is the presumptive polypide. Down-stream components of the canonical Wnt signaling pathway were exclusively expressed in the blastemas. Bn?catenin and BnFz5/8 were exclusively expressed in the blastemas throughout the metamorphosis. Based on the genes expression patterns, we propose that BnWnt10 and BnsFRP may relate to the patterning of the polypide, in which the two genes served as positional signals and contributed to the polarization of the blastemas. Another Wnt ligand, BnWnt6, was expressed in the apical part of the pre-ancestrula epidermis. Overall, our findings suggest that the Wnt signaling pathway may be important to the pattern formation of polypide and the development of epidermis. © 2012 Wong et al.

  8. Association analysis of canonical Wnt signalling genes in diabetic nephropathy.

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    David H Kavanagh

    Full Text Available Several studies have provided compelling evidence implicating the Wnt signalling pathway in the pathogenesis of diabetic nephropathy. Gene expression profiles associated with renal fibrosis have been attenuated through Wnt pathway modulation in model systems implicating Wnt pathway members as potential therapeutic targets for the treatment of diabetic nephropathy. We assessed tag and potentially functional single nucleotide polymorphisms (SNPs; n = 31 in four key Wnt pathway genes (CTNNB1, AXIN2, LRP5 and LRP6 for association with diabetic nephropathy using a case-control design.SNPs were genotyped using Sequenom or Taqman technologies in 1351 individuals with type 1 diabetes (651 cases with nephropathy and 700 controls without nephropathy. Cases and controls were white and recruited from the UK and Ireland. Association analyses were performed using PLINK, to compare allele and haplotype frequencies in cases and controls. Adjustment for multiple testing was performed by permutation testing.Following logistic regression analysis adjusted by collection centre, duration of T1D, and average HbA1c as covariates, a single SNP in LRP6 (rs1337791 was significantly associated with DN (OR = 0.74; CI: 0.57-0.97; P = 0.028, although this was not maintained following correction for multiple testing. Three additional SNPs (rs2075241 in LRP6; rs3736228 and rs491347 both in LRP5 were marginally associated with diabetic nephropathy, but none of the associations were replicated in an independent dataset. Haplotype and subgroup analysis (according to duration of diabetes, and end-stage renal disease also failed to reveal an association with diabetic nephropathy.Our results suggest that analysed common variants in CTNNB1, AXIN2, LRP5 and LRP6 are not strongly associated with diabetic nephropathy in type 1 diabetes among white individuals. Our findings, however, cannot entirely exclude these genes or other members of the Wnt pathway, from involvement in

  9. Canonical Wnt signaling activity in early stages of chick lung development.

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    Rute Silva Moura

    Full Text Available Wnt signaling pathway is an essential player during vertebrate embryonic development which has been associated with several developmental processes such as gastrulation, body axis formation and morphogenesis of numerous organs, namely the lung. Wnt proteins act through specific transmembrane receptors, which activate intracellular pathways that regulate cellular processes such as cell proliferation, differentiation and death. Morphogenesis of the fetal lung depends on epithelial-mesenchymal interactions that are governed by several growth and transcription factors that regulate cell proliferation, fate, migration and differentiation. This process is controlled by different signaling pathways such as FGF, Shh and Wnt among others. Wnt signaling is recognized as a key molecular player in mammalian pulmonary development but little is known about its function in avian lung development. The present work characterizes, for the first time, the expression pattern of several Wnt signaling members, such as wnt-1, wnt-2b, wnt-3a, wnt-5a, wnt-7b, wnt-8b, wnt-9a, lrp5, lrp6, sfrp1, dkk1, β-catenin and axin2 at early stages of chick lung development. In general, their expression is similar to their mammalian counterparts. By assessing protein expression levels of active/total β-catenin and phospho-LRP6/LRP6 it is revealed that canonical Wnt signaling is active in this embryonic tissue. In vitro inhibition studies were performed in order to evaluate the function of Wnt signaling pathway in lung branching. Lung explants treated with canonical Wnt signaling inhibitors (FH535 and PK115-584 presented an impairment of secondary branch formation after 48 h of culture along with a decrease in axin2 expression levels. Branching analysis confirmed this inhibition. Wnt-FGF crosstalk assessment revealed that this interaction is preserved in the chick lung. This study demonstrates that Wnt signaling is crucial for precise chick lung branching and further supports the

  10. The role of Wnt signaling in neuronal dysfunction in Alzheimer's Disease

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    Toledo Enrique M

    2008-07-01

    Full Text Available Abstract Recent evidence supports a neuroprotective role for Wnt signaling in neurodegenerative disorders such as Alzheimer's Disease (AD. In fact, a relationship between amyloid-β-peptide (Aβ-induced neurotoxicity and a decrease in the cytoplasmic levels of β-catenin has been observed. Apparently Aβ binds to the extracellular cysteine-rich domain of the Frizzled receptor (Fz inhibiting Wnt/β-catenin signaling. Cross-talk with other signaling cascades that regulate Wnt/β-catenin signaling, including the activation of M1 muscarinic receptor and PKC, the use of Ibuprofen-ChE bi-functional compounds, PPAR α, γ agonists, nicotine and some antioxidants, results in neuroprotection against Aβ. These studies indicate that a sustained loss of Wnt signaling function may be involved in the Aβ-dependent neurodegeneration observed in Alzheimer's brain. In conclusion the activation of the Wnt signaling pathway could be proposed as a therapeutic target for the treatment of AD.

  11. Zebrafish Ext2 is necessary for Fgf and Wnt signaling, but not for Hh signaling.

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    Fischer, Sabine; Filipek-Gorniok, Beata; Ledin, Johan

    2011-09-05

    Heparan sulfate (HS) biosynthesis is tightly regulated during vertebrate embryo development. However, potential roles for HS biosynthesis in regulating the function of paracrine signaling molecules that bind to HS are incompletely understood. In this report we have studied Fgf, Wnt and Hedgehog (Hh) signaling in ext2 mutants, where heparan sulfate content is low. We found that Fgf targeted gene expression is reduced in ext2 mutants and that the remaining expression is readily inhibited by SU5402, an FGF receptor inhibitor. In the ext2 mutants, Fgf signaling is shown to be affected during nervous system development and reduction of Fgf ligands in the mutants affects tail development. Also, Wnt signaling is affected in the ext2 mutants, as shown by a stronger phenotype in ext2 mutants injected with morpholinos that partially block translation of Wnt11 or Wnt5b, compared to injected wild type embryos. In contrast, Hh dependent signaling is apparently unaffected in the ext2 mutants; Hh targeted gene expression is not reduced, the Hh inhibitor cyclopamine is not more affective in the mutants and Hh dependent cell differentiation in the retina and in the myotome are normal in ext2 mutants. In addition, no genetic interaction between ext2 and shha during development could be detected. We conclude that ext2 is involved in Fgf and Wnt signaling but not in Hh signaling, revealing an unexpected specificity for ext2 in signaling pathways during embryonic development. Thus, our results support the hypothesis that regulation of heparan sulfate biosynthesis has distinct instructive functions for different signaling factors.

  12. A dual role of the Wnt signaling pathway during aging in Caenorhabditis elegans

    NARCIS (Netherlands)

    Lezzerini, M.; Budovskaya, Y.

    2014-01-01

    Wnt signaling is a major and highly conserved developmental pathway that guides many important events during embryonic and larval development. In adulthood, misregulation of Wnt signaling has been implicated in tumorigenesis and various age-related diseases. These effects occur through highly

  13. TLR4 Activation Promotes Bone Marrow MSC Proliferation and Osteogenic Differentiation via Wnt3a and Wnt5a Signaling.

    Science.gov (United States)

    He, Xiaoqing; Wang, Hai; Jin, Tao; Xu, Yongqing; Mei, Liangbin; Yang, Jun

    2016-01-01

    Mesenchymal stem cells (MSCs) from adult bone marrow maintain their self-renewal ability and the ability to differentiate into osteoblast. Thus, adult bone marrow MSCs play a key role in the regeneration of bone tissue. Previous studies indicated that TLR4 is expressed in MSCs and is critical in regulating the fate decision of MSCs. However, the exact functional role and underlying mechanisms of how TLR4 regulate bone marrow MSC proliferation and differentiation are unclear. Here, we found that activated TLR4 by its ligand LPS promoted the proliferation and osteogenic differentiation of MSCs in vitro. TLR4 activation by LPS also increased cytokine IL-6 and IL-1β production in MSCs. In addition, LPS treatment has no effect on inducing cell death of MSCs. Deletion of TLR4 expression in MSCs completely eliminated the effects of LPS on MSC proliferation, osteogenic differentiation and cytokine production. We also found that the mRNA and protein expression of Wnt3a and Wnt5a, two important factors in regulating MSC fate decision, was upregulated in a TLR4-dependent manner. Silencing Wnt3a with specific siRNA remarkably inhibited TLR4-induced MSC proliferation, while Wnt5a specific siRNA treatment significantly antagonized TLR4-induced MSC osteogenic differentiation. These results together suggested that TLR4 regulates bone marrow MSC proliferation and osteogenic differentiation through Wnt3a and Wnt5a signaling. These finding provide new data to understand the role and the molecular mechanisms of TLR4 in regulating bone marrow MSC functions. These data also provide new insight in developing new therapy in bone regeneration using MSCs by modulating TLR4 and Wnt signaling activity.

  14. Wnt/β-catenin signaling promotes regeneration after adult zebrafish spinal cord injury.

    Science.gov (United States)

    Strand, Nicholas S; Hoi, Kimberly K; Phan, Tien M T; Ray, Catherine A; Berndt, Jason D; Moon, Randall T

    2016-09-02

    Unlike mammals, zebrafish can regenerate their injured spinal cord and regain control of caudal tissues. It was recently shown that Wnt/β-catenin signaling is necessary for spinal cord regeneration in the larval zebrafish. However, the molecular mechanisms of regeneration may or may not be conserved between larval and adult zebrafish. To test this, we assessed the role of Wnt/β-catenin signaling after spinal cord injury in the adult zebrafish. We show that Wnt/β-catenin signaling is increased after spinal cord injury in the adult zebrafish. Moreover, overexpression of Dkk1b inhibited Wnt/β-catenin signaling in the regenerating spinal cord of adult zebrafish. Dkk1b overexpression also inhibited locomotor recovery, axon regeneration, and glial bridge formation in the injured spinal cord. Thus, our data illustrate a conserved role for Wnt/β-catenin signaling in adult and larval zebrafish spinal cord regeneration. Published by Elsevier Inc.

  15. Inhibition of adipocytogenesis by canonical WNT signaling in human mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Longxiang; Glowacki, Julie; Zhou, Shuanhu, E-mail: szhou@rics.bwh.harvard.edu

    2011-08-01

    The WNT signaling pathway plays important roles in the self-renewal and differentiation of mesenchymal stem cells (MSCs). Little is known about WNT signaling in adipocyte differentiation of human MSCs. In this study, we tested the hypothesis that canonical and non-canonical WNTs differentially regulate in vitro adipocytogenesis in human MSCs. The expression of adipocyte gene PPAR{gamma}2, lipoprotein lipase, and adipsin increased during adipocytogenesis of hMSCs. Simultaneously, the expression of canonical WNT2, 10B, 13, and 14 decreased, whereas non-canonical WNT4 and 11 increased, and WNT5A was unchanged. A small molecule WNT mimetic, SB-216763, increased accumulation of {beta}-catenin protein, inhibited induction of WNT4 and 11 and inhibited adipocytogenesis. In contrast, knockdown of {beta}-catenin with siRNA resulted in spontaneous adipocytogenesis. These findings support the view that canonical WNT signaling inhibits and non-canonical WNT signaling promotes adipocytogenesis in adult human marrow-derived mesenchymal stem cells.

  16. Detection of Transient Signals in Doppler Spectra

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Signal processing is used to detect transient signals in the presence of noise. Two embodiments are disclosed. In both embodiments, the time series from a remote...

  17. Wnt signaling during tooth replacement in zebrafish (Danio rerio): pitfalls and perspectives

    Science.gov (United States)

    Huysseune, Ann; Soenens, Mieke; Elderweirdt, Fien

    2014-01-01

    The canonical (β-catenin dependent) Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1) in developing zebrafish (Danio rerio) tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl) mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement. The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i) potential technical pitfalls related to dose- or time-dependency, (ii) the complexity of the canonical Wnt pathway, and (iii) species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts. PMID

  18. Wnt signaling during tooth replacement in zebrafish (Danio rerio: pitfalls and perspectives

    Directory of Open Access Journals (Sweden)

    Ann eHuysseune

    2014-10-01

    Full Text Available The canonical (β-catenin dependent Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1 in developing zebrafish (Danio rerio tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement.The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i potential technical pitfalls related to dose- or time-dependency, (ii the complexity of the canonical Wnt pathway, and (iii species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts.

  19. Role of SDF-1 and Wnt signaling pathway in the myocardial fibrosis of hypertensive rats.

    Science.gov (United States)

    Shao, Shuai; Cai, Wenwei; Sheng, Jing; Yin, Lingni

    2015-01-01

    To investigate the effects of stromal cell-derived factor-1 (SDF-1) and Wnt signaling pathway on the bioactivities of myofibroblasts (MFs) and the expressions of SDF-1 and components of Wnt signaling pathway in the myocardium of spontaneously hypertensive rats (SHR). BMSCs were induced to differentiate into MFs in vitro, and SDF-1 and Wnt signaling pathway were independently or simultaneously blocked. Then, the migration of MFs and the secretion of Col I and α-SMA were determined in MFs. Heart function, progression of myocardial fibrosis and structure of the heart were evaluated. The expression of SDF-1 and components of Wnt signaling pathway in SHR was detected. TGF-β could induce the differentiation of BMSCs into B-MFs; Blocking SDF-1/CXCR4 axis and/or Wnt signaling pathway was able to inhibit the MFs migration and Col I secretion; Blocking Wnt signaling pathway inhibited the differentiation of BMSCs into MFs; Serum SDF-1 increased with the increase in blood pressure, and serum β-catenin elevated with the fluctuation of blood pressure; Protein and mRNA expressions of SDF-1 in the myocardium increased, and those of DKK-1 (an inhibitor of Wnt signaling pathway) and GSK-3 reduced in SHR. SDF-1 and Wnt signaling pathway are involved in the differentiation of BMSCs into MFs, as well as the migration and collagen secretion of MFs; Hypertension affects the expressions of SDF-1 and components of Wnt signaling pathway. In the myocardium of SHR, SDF-1 expression increases, but the expression of inhibitor of Wnt signaling pathway reduces.

  20. Remote activation of the Wnt/β-catenin signalling pathway using functionalised magnetic particles.

    Directory of Open Access Journals (Sweden)

    Michael Rotherham

    Full Text Available Wnt signalling pathways play crucial roles in developmental biology, stem cell fate and tissue patterning and have become an attractive therapeutic target in the fields of tissue engineering and regenerative medicine. Wnt signalling has also been shown to play a role in human Mesenchymal Stem Cell (hMSC fate, which have shown potential as a cell therapy in bone and cartilage tissue engineering. Previous work has shown that biocompatible magnetic nanoparticles (MNP can be used to stimulate specific mechanosensitive membrane receptors and ion channels in vitro and in vivo. Using this strategy, we determined the effects of mechano-stimulation of the Wnt Frizzled receptor on Wnt pathway activation in hMSC. Frizzled receptors were tagged using anti-Frizzled functionalised MNP (Fz-MNP. A commercially available oscillating magnetic bioreactor (MICA Biosystems was used to mechanically stimulate Frizzled receptors remotely. Our results demonstrate that Fz-MNP can activate Wnt/β-catenin signalling at key checkpoints in the signalling pathway. Immunocytochemistry indicated nuclear localisation of the Wnt intracellular messenger β-catenin after treatment with Fz-MNP. A Wnt signalling TCF/LEF responsive luciferase reporter transfected into hMSC was used to assess terminal signal activation at the nucleus. We observed an increase in reporter activity after treatment with Fz-MNP and this effect was enhanced after mechano-stimulation using the magnetic array. Western blot analysis was used to probe the mechanism of signalling activation and indicated that Fz-MNP signal through an LRP independent mechanism. Finally, the gene expression profiles of stress response genes were found to be similar when cells were treated with recombinant Wnt-3A or Fz-MNP. This study provides proof of principle that Wnt signalling and Frizzled receptors are mechanosensitive and can be remotely activated in vitro. Using magnetic nanoparticle technology it may be possible to modulate

  1. Hepatoprotective effect of hesperidin in hepatocellular carcinoma: Involvement of Wnt signaling pathways.

    Science.gov (United States)

    Zaghloul, Randa A; Elsherbiny, Nehal M; Kenawy, Hany I; El-Karef, Amr; Eissa, Laila A; El-Shishtawy, Mamdouh M

    2017-09-15

    Wnt3a and Wnt5a are ligands orchestrating the canonical and non-canonical pathways, respectively, with involvement in hepatocellular carcinoma (HCC). Hesperidin (HP) is a natural product found in citrus fruits and reputed for its antitumor activity. The present study aims to investigate the potential hepatoprotective effect of HP against thioacetamide (TAA)-induced HCC focusing on its potential role on Wnt3a and Wnt5a signaling pathways. Forty rats were equally divided into groups; normal control, HP control (receiving HP, 150mg/kg/day), HCC (receiving TAA, 200mg/kg twice weekly for 14weeks) and HP-HCC (receiving HP and TAA). Gene expressions of Wnt3a, Wnt5a, β-catenin and Cyclin D1 were assessed by qPCR, while their protein levels, along with active caspase-3 level, were quantified by ELISA and immunohistochemistry. Liver functions, oxidative stress parameters and myeloperoxidase activity were measured. MTT assay of hepG2 cells treated with recombinant Wnt3a (10ng/ml) in presence or absence of HP (100μM) was performed. HCC group exhibited a significant increase in Wnt3a, β-catenin, Cyclin D1 and Wnt5a gene expressions, as well as, their protein levels. HP significantly prevented TAA-activated Wnt3a/β-catenin and Wnt5a pathways. Moreover, HP exerted hepatoprotective effect by significantly improving the oxidative imbalance, inflammation and liver function parameters, serum ALT, AST activities, and albumin level. Our study is the first to report the possible role of Wnt3a/β-catenin and Wnt5a pathways in TAA-induced early HCC model in rats. HP has a prophylactic effect against hepatocarcinogenesis via preventing the induction of both canonical and non-canonical Wnt pathways. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Microglia-Induced Activation of Noncanonical Wnt Signaling Aggravates Neurodegeneration in Demyelinating Disorders

    Science.gov (United States)

    Smits, Ron; Ikenaka, Kazuhiro

    2016-01-01

    Oligodendrocytes are myelinating cells of the central nervous system. Multiple sclerosis (MS) is a demyelinating disease characterized by both myelin loss and neuronal degeneration. However, the molecular mechanisms underlying neuronal degeneration in demyelinating disorders are not fully understood. In the experimental autoimmune encephalomyelitis (EAE) demyelinating-mouse model of MS, inflammatory microglia produce cytokines, including interleukin-1β (IL-1β). Since microglia and noncanonical Wnt signaling components in neurons, such as the coreceptor Ror2, were observed in the spinal cords of mice with EAE (EAE mice), we postulated that the interplay between activated microglia and spinal neurons under EAE conditions is mediated through noncanonical Wnt signaling. EAE treatment upregulated in vivo expression of noncanonical Wnt signaling components in spinal neurons through microglial activation. In accordance with the neuronal degeneration detected in the EAE spinal cord in vivo, coculture of spinal neurons with microglia or the application of recombinant IL-1β upregulated noncanonical Wnt signaling and induced neuron death, which was suppressed by the inhibition of the Wnt-Ror2 pathway. Ectopic noncanonical Wnt signaling aggravated the demyelinating pathology in another MS mouse model due to Wnt5a-induced neurodegeneration. The linkage between activated microglia and neuronal Wnt-Ror2 signaling may provide a candidate target for therapeutic approaches to demyelinating disorders. PMID:27550808

  3. Interrelationship of canonical and non-canonical Wnt signalling pathways in chronic metabolic diseases.

    Science.gov (United States)

    Ackers, Ian; Malgor, Ramiro

    2018-01-01

    Chronic diseases account for approximately 45% of all deaths in developed countries and are particularly prevalent in countries with the most sophisticated and robust public health systems. Chronic metabolic diseases, specifically lifestyle-related diseases pertaining to diet and exercise, continue to be difficult to treat clinically. The most prevalent of these chronic metabolic diseases include obesity, diabetes, non-alcoholic fatty liver disease, chronic kidney disease and cardiovascular disease and will be the focus of this review. Wnt proteins are highly conserved glycoproteins best known for their role in development and homeostasis of tissues. Given the importance of Wnt signalling in homeostasis, aberrant Wnt signalling likely regulates metabolic processes and may contribute to the development of chronic metabolic diseases. Expression of Wnt proteins and dysfunctional Wnt signalling has been reported in multiple chronic diseases. It is interesting to speculate about an interrelationship between the Wnt signalling pathways as a potential pathological mechanism in chronic metabolic diseases. The aim of this review is to summarize reported findings on the contrasting roles of Wnt signalling in lifestyle-related chronic metabolic diseases; specifically, the contribution of Wnt signalling to lipid accumulation, fibrosis and chronic low-grade inflammation.

  4. Wnt5a-Ror-Dishevelled signaling constitutes a core developmental pathway that controls tissue morphogenesis.

    Science.gov (United States)

    Ho, Hsin-Yi Henry; Susman, Michael W; Bikoff, Jay B; Ryu, Yun Kyoung; Jonas, Andrea M; Hu, Linda; Kuruvilla, Rejji; Greenberg, Michael Eldon

    2012-03-13

    Wnts make up a large family of extracellular signaling molecules that play crucial roles in development and disease. A subset of noncanonical Wnts signal independently of the transcription factor β-catenin by a mechanism that regulates key morphogenetic movements during embryogenesis. The best characterized noncanonical Wnt, Wnt5a, has been suggested to signal via a variety of different receptors, including the Ror family of receptor tyrosine kinases, the Ryk receptor tyrosine kinase, and the Frizzled seven-transmembrane receptors. Whether one or several of these receptors mediates the effects of Wnt5a in vivo is not known. Through loss-of-function experiments in mice, we provide conclusive evidence that Ror receptors mediate Wnt5a-dependent processes in vivo and identify Dishevelled phosphorylation as a physiological target of Wnt5a-Ror signaling. The absence of Ror signaling leads to defects that mirror phenotypes observed in Wnt5a null mutant mice, including decreased branching of sympathetic neuron axons and major defects in aspects of embryonic development that are dependent upon morphogenetic movements, such as severe truncation of the caudal axis, the limbs, and facial structures. These findings suggest that Wnt5a-Ror-Dishevelled signaling constitutes a core noncanonical Wnt pathway that is conserved through evolution and is crucial during embryonic development.

  5. Microglia-induced activation of non-canonical Wnt signaling aggravates neurodegeneration in demyelinating disorders.

    Science.gov (United States)

    Shimizu, Takeshi; Smits, Ron; Ikenaka, Kazuhiro

    2016-08-22

    Oligodendrocytes are myelinating cells of the central nervous system. Multiple sclerosis (MS) is a demyelinating disease characterized by both myelin loss and neuronal degeneration. However, the molecular mechanisms underlying neuronal degeneration in demyelinating disorders are not fully understood. In the experimental autoimmune encephalomyelitis (EAE) demyelinating mouse model of MS, inflammatory microglia produce cytokines including interleukin-1β (IL-1β). Since microglia and non-canonical Wnt signaling components in neurons, such as the co-receptor Ror2, were observed in the spinal cord of EAE mice, we postulated that the interplay between activated microglia and spinal neurons under EAE conditions is mediated through non-canonical Wnt signaling. EAE treatment up-regulated in vivo expression of non-canonical Wnt signaling components in spinal neurons through microglial activation. In accordance with the neuronal degeneration detected in the EAE spinal cord in vivo, co-culture of spinal neurons with microglia or the application of recombinant IL-1β up-regulated non-canonical Wnt signaling, and induced neuronal cell death, which was suppressed by the inhibition of the Wnt-Ror2 pathway. Ectopic non-canonical Wnt signaling aggravated the demyelinating pathology in another MS mouse model due to Wnt5a-induced neurodegeneration. The linkage between activated microglia and neuronal Wnt-Ror2 signaling may provide a possible candidate target for therapeutic approaches to demyelinating disorders. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  6. The non-canonical BMP and Wnt/β-catenin signaling pathways orchestrate early tooth development.

    Science.gov (United States)

    Yuan, Guohua; Yang, Guobin; Zheng, Yuqian; Zhu, Xiaojing; Chen, Zhi; Zhang, Zunyi; Chen, YiPing

    2015-01-01

    BMP and Wnt signaling pathways play a crucial role in organogenesis, including tooth development. Despite extensive studies, the exact functions, as well as if and how these two pathways act coordinately in regulating early tooth development, remain elusive. In this study, we dissected regulatory functions of BMP and Wnt pathways in early tooth development using a transgenic noggin (Nog) overexpression model (K14Cre;pNog). It exhibits early arrested tooth development, accompanied by reduced cell proliferation and loss of odontogenic fate marker Pitx2 expression in the dental epithelium. We demonstrated that overexpression of Nog disrupted BMP non-canonical activity, which led to a dramatic reduction of cell proliferation rate but did not affect Pitx2 expression. We further identified a novel function of Nog by inhibiting Wnt/β-catenin signaling, causing loss of Pitx2 expression. Co-immunoprecipitation and TOPflash assays revealed direct binding of Nog to Wnts to functionally prevent Wnt/β-catenin signaling. In situ PLA and immunohistochemistry on Nog mutants confirmed in vivo interaction between endogenous Nog and Wnts and modulation of Wnt signaling by Nog in tooth germs. Genetic rescue experiments presented evidence that both BMP and Wnt signaling pathways contribute to cell proliferation regulation in the dental epithelium, with Wnt signaling also controlling the odontogenic fate. Reactivation of both BMP and Wnt signaling pathways, but not of only one of them, rescued tooth developmental defects in K14Cre;pNog mice, in which Wnt signaling can be substituted by transgenic activation of Pitx2. Our results reveal the orchestration of non-canonical BMP and Wnt/β-catenin signaling pathways in the regulation of early tooth development. © 2015. Published by The Company of Biologists Ltd.

  7. ME-143 Is Superior to Genistein in Suppression of WNT Signaling in Colon Cancer Cells.

    Science.gov (United States)

    Pintova, Sofya; Planutis, Kestutis; Planutiene, Marina; Holcombe, Randall F

    2017-04-01

    This study tested the effect of the soy isoflavones genistein and ME-143, and two chemotherapeutic agents, 5-fluorouracil (5FU) and oxaliplatin, on WNT signaling. Colon cancer cell lines RKO (hereditary nonpolyposis colorectal cancer type) and DLD1 (most common colorectal cancer type driven by a mutation in WNT pathway) were utilized. WNT throughput was measured using a β-catenin-responsive SuperTopFlash luciferase assay. A stabilized β-catenin construct was employed to test β-catenin involvement in the mechanism of drug activity. ME-143 was a more than 10-fold potent inhibitor of DLD1 proliferation than genistein at 3.125 μM. Genistein alone did not inhibit WNT signaling in either cell line. In RKO cells, oxaliplatin and its combination with 5FU significantly inhibited WNT throughput. Neither 5FU, oxaliplatin nor their combination inhibited WNT signaling in DLD1 cells. In both the RKO and DLD1 cell lines, ME-143 significantly reduced WNT throughput by 65-75%. The introduction of stabilized β-catenin attenuated the ME-143-dependent inhibition of the WNT/β-catenin pathway. ME-143 alone and in combination with 5FU and oxaliplatin effectively inhibits the WNT/β-catenin pathway in colorectal cancer cells of diverse genetic background. β-Catenin is directly involved in the mechanism of inhibition, and clinical studies are warranted. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  8. SLIT/ROBO2 Signaling Promotes Mammary Stem Cell Senescence by Inhibiting Wnt Signaling

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    Gwyndolen Harburg

    2014-09-01

    Full Text Available WNT signaling stimulates the self-renewal of many types of adult stem cells, including mammary stem cells (MaSCs, but mechanisms that limit this activity are poorly understood. Here, we demonstrate that SLIT2 restricts stem cell renewal by signaling through ROBO2 in a subset of basal cells to negatively regulate WNT signaling. The absence of SLIT/ROBO2 signaling leads to increased levels of nuclear β-catenin. Robo2 loss does not increase the number of stem cells; instead, stem cell renewal is enhanced in the absence of SLIT/ROBO2 signaling. This is due to repressed expression of p16 INK4a, which, in turn, delays MaSC senescence. Together, our studies support a model in which SLITs restrict the expansion of MaSCs by countering the activity of WNTs and limiting self-renewal.

  9. Making sense of Wnt signaling – linking hair cell regeneration to development

    Directory of Open Access Journals (Sweden)

    Lina eJansson

    2015-03-01

    Full Text Available Wnt signaling is a highly conserved pathway crucial for development and homeostasis of multicellular organisms. Secreted Wnt ligands bind Frizzled receptors to regulate diverse processes such as axis patterning, cell division, and cell fate specification. They also serve to govern self-renewal of somatic stem cells in several adult tissues. The complexity of the pathway can be attributed to the myriad of Wnt and Frizzled combinations as well as its diverse context-dependent functions. In the developing mouse inner ear, Wnt signaling plays diverse roles, including specification of the otic placode and patterning of the otic vesicle. At later stages, its activity governs sensory hair cell specification, cell cycle regulation, and hair cell orientation. In regenerating sensory organs from non-mammalian species, Wnt signaling can also regulate the extent of proliferative hair cell regeneration. This review describes the current knowledge of the roles of Wnt signaling and Wnt-responsive cells in hair cell development and regeneration. We also discuss possible future directions and the potential application and limitation of Wnt signaling in augmenting hair cell regeneration.

  10. FGF signaling inhibitor, SPRY4, is evolutionarily conserved target of WNT signaling pathway in progenitor cells.

    Science.gov (United States)

    Katoh, Yuriko; Katoh, Masaru

    2006-03-01

    WNT, FGF and Hedgehog signaling pathways network together during embryogenesis, tissue regeneration, and carcinogenesis. FGF16, FGF18, and FGF20 genes are targets of WNT-mediated TCF/LEF-beta-catenin-BCL9/BCL9L-PYGO transcriptional complex. SPROUTY (SPRY) and SPRED family genes encode inhibitors for receptor tyrosine kinase signaling cascades, such as those of FGF receptor family members and EGF receptor family members. Here, transcriptional regulation of SPRY1, SPRY2, SPRY3, SPRY4, SPRED1, SPRED2, and SPRED3 genes by WNT/beta-catenin signaling cascade was investigated by using bioinformatics and human intelligence (humint). Because double TCF/LEF-binding sites were identified within the 5'-promoter region of human SPRY4 gene, comparative genomics analyses on SPRY4 orthologs were further performed. SPRY4-FGF1 locus at human chromosome 5q31.3 and FGF2-NUDT6-SPATA5-SPRY1 locus at human chromosome 4q27-q28.1 were paralogous regions within the human genome. Chimpanzee SPRY4 gene was identified within NW_107083.1 genome sequence. Human, chimpanzee, rat and mouse SPRY4 orthologs, consisting of three exons, were well conserved. SPRY4 gene was identified as the evolutionarily conserved target of WNT/beta-catenin signaling pathway based on the conservation of double TCF/LEF-binding sites within 5'-promoter region of mammalian SPRY4 orthologs. Human SPRY4 mRNA was expressed in embryonic stem (ES) cells, brain, pancreatic islet, colon cancer, head and neck tumor, melanoma, and pancreatic cancer. WNT signaling activation in progenitor cells leads to the growth regulation of progenitor cells themselves through SPRY4 induction, and also to the growth stimulation of proliferating cells through FGF secretion. Epigenetic silencing and loss-of-function mutations of SPRY4 gene in progenitor cells could lead to carcinogenesis. SPRY4 is the pharmacogenomics target in the fields of oncology and regenerative medicine.

  11. A Dynamic WNT/β-CATENIN Signaling Environment Leads to WNT-Independent and WNT-Dependent Proliferation of Embryonic Intestinal Progenitor Cells

    Directory of Open Access Journals (Sweden)

    Alana M. Chin

    2016-11-01

    Full Text Available Much of our understanding about how intestinal stem and progenitor cells are regulated comes from studying the late fetal stages of development and the adult intestine. In this light, little is known about intestine development prior to the formation of stereotypical villus structures with columnar epithelium, a stage when the epithelium is pseudostratified and appears to be a relatively uniform population of progenitor cells with high proliferative capacity. Here, we investigated a role for WNT/β-CATENIN signaling during the pseudostratified stages of development (E13.5, E14.5 and following villus formation (E15.5 in mice. In contrast to the well-described role for WNT/β-CATENIN signaling as a regulator of stem/progenitor cells in the late fetal and adult gut, conditional epithelial deletion of β-catenin or the Frizzled co-receptors Lrp5 and Lrp6 had no effect on epithelial progenitor cell proliferation in the pseudostratified epithelium. Mutant embryos displayed obvious developmental defects, including loss of proliferation and disruptions in villus formation starting only at E15.5. Mechanistically, our data suggest that WNT signaling-mediated proliferation at the time of villus formation is driven by mesenchymal, but not epithelial, WNT ligand secretion.

  12. A Glimpse of the Pathogenetic Mechanisms of Wnt/β-Catenin Signaling in Diabetic Nephropathy

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    Li Xiao

    2013-01-01

    Full Text Available The Wnt family of proteins belongs to a group of secreted lipid-modified glycoproteins with highly conserved cysteine residues. Prior results indicate that Wnt/β-catenin signaling plays a prominent role in cell differentiation, adhesion, survival, and apoptosis and is involved in organ development, tumorigenesis, and tissue fibrosis, among other functions. Accumulating evidence has suggested that Wnt/β-catenin exhibits a pivotal function in the progression of diabetic nephropathy (DN. In this review, we focused on discussing the dual role of Wnt/β-catenin in apoptosis and epithelial mesenchymal transition (EMT formation of mesangial cells. Moreover, we also elucidated the effect of Wnt/β-catenin in podocyte dysfunction, tubular EMT formation, and renal fibrosis under DN conditions. In addition, the molecular mechanisms involved in this process are introduced. This information provides a novel molecular target of Wnt/β-catenin for the protection of kidney damage and in delay of the progression of DN.

  13. Merlin, a regulator of Hippo signaling, regulates Wnt/β-catenin signaling.

    Science.gov (United States)

    Kim, Soyoung; Jho, Eek-Hoon

    2016-07-01

    Merlin, encoded by the NF2 gene, is a tumor suppressor that exerts its function via inhibiting mitogenic receptors at the plasma membrane. Although multiple mutations in Merlin have been identified in Neurofibromatosis type II (NF2) disease, its molecular mechanism is not fully understood. Here, we show that Merlin interacts with LRP6 and inhibits LRP6 phosphorylation, a critical step for the initiation of Wnt signaling. We found that treatment of Wnt3a caused phosphorylation of Merlin by PAK1, leading to detachment of Merlin from LRP6 and allowing the initiation of Wnt/β-catenin signaling. A higher level of β-catenin was found in tissues from NF2 patients. Enhanced proliferation and migration caused by knockdown of Merlin in glioblastoma cells were inhibited by suppression of β-catenin. Conclusively, these results suggest that sustained Wnt/β-catenin signaling activity induced by abrogation of Merlin-mediated inhibition of LRP6 phosphorylation might be a cause of NF2 disease. [BMB Reports 2016; 49(7): 357-358].

  14. Effects of Wnt signaling on brown adipocyte differentiation and metabolism mediated by PGC-1alpha

    DEFF Research Database (Denmark)

    Kang, Sona; Bajnok, Laszlo; Longo, Kenneth A

    2005-01-01

    expression of PGC-1alpha is required for activation of uncoupling protein 1 (UCP1). Wnt10b blocks brown adipose tissue development and expression of UCP1 when expressed from the fatty acid binding protein 4 promoter, even when mice are administered a beta3-agonist. In differentiated brown adipocytes...... expression of PGC-1alpha and UCP1, the presence of unilocular lipid droplets and expression of white adipocyte genes suggest conversion of brown adipose tissue to white. Reciprocal expression of Wnt10b with UCP1 and PGC-1alpha in interscapular tissue from cold-challenged or genetically obese mice provides...... further evidence for regulation of brown adipocyte metabolism by Wnt signaling. Taken together, these data suggest that activation of canonical Wnt signaling early in differentiation blocks brown adipogenesis, whereas activating Wnt signaling in mature brown adipocytes stimulates their conversion to white...

  15. Blocking Wnt5a signaling decreases CD36 expression and foam cell formation in atherosclerosis.

    Science.gov (United States)

    Ackers, Ian; Szymanski, Candice; Duckett, K Jordan; Consitt, Leslie A; Silver, Mitchell J; Malgor, Ramiro

    2018-02-20

    Wnt5a is a highly studied member of the Wnt family and recently has been implicated in the pathogenesis of atherosclerosis, but its precise role is unknown. Foam cell development is a critical process to atherosclerotic plaque formation. In the present study, we investigated the role of noncanonical Wnt5a signaling in the development of foam cells. Human carotid atherosclerotic tissue and THP-1-derived macrophages were used to investigate the contribution of Wnt5a signaling in the formation of foam cells. Immunohistochemistry was used to evaluate protein expression of scavenger receptors and noncanonical Wnt5a receptors [frizzled 5 (Fz5) and receptor tyrosine kinase-like orphan receptor 2 (Ror2)] in human atherosclerotic macrophages/foam cells. Changes in protein expression in response to Wnt5a stimulation/inhibition were determined by Western blot, and lipid accumulation was evaluated by fluorescent lipid droplet staining. Wnt5a (Pfoam cells within the plaque. In vitro studies revealed that Wnt5a significantly increased the expression of the lipid uptake receptor CD36 (P.05). rWnt5a also significantly increased lipid accumulation in THP-1 macrophages (Pfoam cells. Copyright © 2018. Published by Elsevier Inc.

  16. The role of Ryk and Ror receptor tyrosine kinases in Wnt signal transduction

    NARCIS (Netherlands)

    Green, J.; Nusse, R.; van Amerongen, R.

    2014-01-01

    Receptor tyrosine kinases of the Ryk and Ror families were initially classified as orphan receptors because their ligands were unknown. They are now known to contain functional extracellular Wnt-binding domains and are implicated in Wnt-signal transduction in multiple species. Although their

  17. Wnt-β-Catenin Signaling Promotes the Maturation of Mast Cells

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    Tomoko Yamaguchi

    2016-01-01

    Full Text Available Mast cells play an important role in the pathogenesis of allergic diseases. Immature mast cells migrate into peripheral tissues from the bone marrow and undergo complete maturation. Interestingly, mast cells have characteristics similar to hematopoietic stem cells (HSCs, such as self-renewal and c-kit expression. In HSCs, Wnt signaling is involved in their maintenance and differentiation. On the other hand, the relation between Wnt signaling and mast cell differentiation is poorly understood. To study whether Wnt signals play a role in the maturation of mast cells, we studied the effect of Wnt proteins on mast cell maturation of bone marrow-derived mast cells (BMMCs. The expression levels of CD81 protein and histidine decarboxylase mRNA and activity of mast cell-specific protease were all elevated in BMMCs treated with Wnt5a. In addition, Wnt5a induced the expression of Axin2 and TCF mRNA in BMMCs. These results showed that Wnt5a could promote the maturation of mast cells via the canonical Wnt signaling pathway and provide important insights into the molecular mechanisms underlying the differentiation of mast cells.

  18. Silica Nanoparticles Target a Wnt Signal Transducer for Degradation and Impair Embryonic Development in Zebrafish.

    Science.gov (United States)

    Yi, Hongyang; Wang, Zhuyao; Li, Xiaojiao; Yin, Min; Wang, Lihua; Aldalbahi, Ali; El-Sayed, Nahed Nasser; Wang, Hui; Chen, Nan; Fan, Chunhai; Song, Haiyun

    2016-01-01

    Many types of biocompatible nanomaterials have proven of low cytotoxicity and hold great promise for various applications in nanomedicine. Whereas they generally do not cause apparent organ toxicity or tissue damage in adult animals, it is yet to determine their biological consequences in more general contexts. In this study, we investigate how silica nanoparticles (NPs) affect cellular activities and functions under several physiological or pathological conditions. Although silica NPs are generally regarded as "inert" nanocarriers and widely employed in biomedical studies, we find that they actively affect Wnt signaling in various types of cell lines, diminishing its anti-adipogenic effect in preadipocytes and pro-invasive effect in breast cancer cells, and more significantly, impair Wnt-regulated embryonic development in Zebrafish. We further demonstrate that intracellular silica NPs block Wnt signal transduction in a way resembling signaling molecules. Specifically, silica NPs target the Dvl protein, a key component of Wnt signaling cascade, for lysosomal degradation. As Wnt signaling play significant roles in embryonic development and adipogenesis, the observed physiological effects beyond toxicity imply potential risk of obesity, or developmental defects in somitogenesis and osteogenesis upon exposure to silica NPs. In addition, given the clinical implications of Wnt signaling in tumorigenesis and cancer metastasis, our work also establishes for the first time a molecular link between nanomaterials and the Wnt signaling pathway, which opens new door for novel applications of unmodified silica NPs in targeted therapy for cancers and other critical illness.

  19. HPV16 E6 and E6AP differentially cooperate to stimulate or augment Wnt signaling

    Energy Technology Data Exchange (ETDEWEB)

    Sominsky, Sophia, E-mail: sophia.tab@gmail.com [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel); Kuslansky, Yael, E-mail: ykuslansky@gmail.com [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel); Shapiro, Beny, E-mail: benyshap@gmail.com [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel); Jackman, Anna, E-mail: jackman@post.tau.ac.il [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel); Haupt, Ygal, E-mail: ygal.haupt@petermac.org [Research Division, The Peter MacCallum Cancer Centre, East Melbourne (Australia); Rosin-Arbesfeld, Rina, E-mail: arina@post.tau.ac.il [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel); Sherman, Levana, E-mail: lsherman@post.tau.ac.il [Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978 (Israel)

    2014-11-15

    The present study investigated the roles of E6 and E6AP in the Wnt pathway. We showed that E6 levels are markedly reduced in cells in which Wnt signaling is activated. Coexpression of wild-type or mutant E6AP (C820A) in Wnt-activated cells stabilized E6 and enhanced Wnt/β-catenin/TCF transcription. Expression of E6AP alone in nonstimulated cells elevated β-catenin level, promoted its nuclear accumulation, and activated β-catenin/TCF transcription. A knockdown of E6AP lowered β-catenin levels. Coexpression with E6 intensified the activities of E6AP. Further experiments proved that E6AP/E6 stabilize β-catenin by protecting it from proteasomal degradation. This function was dependent on the catalytic activity of E6AP, the kinase activity of GSK3β and the susceptibility of β-catenin to GSK3β phosphorylation. Thus, this study identified E6AP as a novel regulator of the Wnt signaling pathway, capable of cooperating with E6 in stimulating or augmenting Wnt/β-catenin signaling, thereby possibly contributing to HPV carcinogenesis. - Highlights: • The roles of E6 and E6AP in the Wnt pathway were investigated. • E6AP stabilizes E6 and enhances E6 activity in augmentation of Wnt signaling. • E6AP cooperates with E6 to stabilize β-catenin and stimulate Wnt/β-catenin signaling. • E6AP and E6 act through different mechanisms to augment or stimulate Wnt signaling.

  20. Noncanonical Wnt signaling promotes osteoclast differentiation and is facilitated by the human immunodeficiency virus protease inhibitor ritonavir

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, Francisco [Division of Hematology-Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY (United States); Oguma, Junya; Brown, Anthony M.C. [Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY (United States); Laurence, Jeffrey, E-mail: jlaurenc@med.cornell.edu [Division of Hematology-Oncology, Department of Medicine, Weill Cornell Medical College, New York, NY (United States)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer First demonstration of direct role for noncanonical Wnt in osteoclast differentiation. Black-Right-Pointing-Pointer Demonstration of Ryk as a Wnt5a/b receptor in inhibition of canonical Wnt signaling. Black-Right-Pointing-Pointer Modulation of noncanonical Wnt signaling by a clinically important drug, ritonavir. Black-Right-Pointing-Pointer Establishes a mechanism for an important clinical problem: HIV-associated bone loss. -- Abstract: Wnt proteins that signal via the canonical Wnt/{beta}-catenin pathway directly regulate osteoblast differentiation. In contrast, most studies of Wnt-related effects on osteoclasts involve indirect changes. While investigating bone mineral density loss in the setting of human immunodeficiency virus (HIV) infection and its treatment with the protease inhibitor ritonavir (RTV), we observed that RTV decreased nuclear localization of {beta}-catenin, critical to canonical Wnt signaling, in primary human and murine osteoclast precursors. This occurred in parallel with upregulation of Wnt5a and Wnt5b transcripts. These Wnts typically stimulate noncanonical Wnt signaling, and this can antagonize the canonical Wnt pathway in many cell types, dependent upon Wnt receptor usage. We now document RTV-mediated upregulation of Wnt5a/b protein in osteoclast precursors. Recombinant Wnt5b and retrovirus-mediated expression of Wnt5a enhanced osteoclast differentiation from human and murine monocytic precursors, processes facilitated by RTV. In contrast, canonical Wnt signaling mediated by Wnt3a suppressed osteoclastogenesis. Both RTV and Wnt5b inhibited canonical, {beta}-catenin/T cell factor-based Wnt reporter activation in osteoclast precursors. RTV- and Wnt5-induced osteoclast differentiation were dependent upon the receptor-like tyrosine kinase Ryk, suggesting that Ryk may act as a Wnt5a/b receptor in this context. This is the first demonstration of a direct role for Wnt signaling pathways and Ryk in

  1. Wnt signaling cross-talks with JH signaling by suppressing Met and gce expression.

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    Mohamed Abdou

    Full Text Available Juvenile hormone (JH plays key roles in controlling insect growth and metamorphosis. However, relatively little is known about the JH signaling pathways. Until recent years, increasing evidence has suggested that JH modulates the action of 20-hydroxyecdysone (20E by regulating expression of broad (br, a 20E early response gene, through Met/Gce and Kr-h1. To identify other genes involved in JH signaling, we designed a novel Drosophila genetic screen to isolate mutations that derepress JH-mediated br suppression at early larval stages. We found that mutations in three Wnt signaling negative regulators in Drosophila, Axin (Axn, supernumerary limbs (slmb, and naked cuticle (nkd, caused precocious br expression, which could not be blocked by exogenous JHA. A similar phenotype was observed when armadillo (arm, the mediator of Wnt signaling, was overexpressed. qRT-PCR revealed that Met, gce and Kr-h1expression was suppressed in the Axn, slmb and nkd mutants as well as in arm gain-of-function larvae. Furthermore, ectopic expression of gce restored Kr-h1 expression but not Met expression in the arm gain-of-function larvae. Taken together, we conclude that Wnt signaling cross-talks with JH signaling by suppressing transcription of Met and gce, genes that encode for putative JH receptors. The reduced JH activity further induces down-regulation of Kr-h1expression and eventually derepresses br expression in the Drosophila early larval stages.

  2. Increased heme-oxygenase 1 expression in mesenchymal stem cell-derived adipocytes decreases differentiation and lipid accumulation via upregulation of the canonical Wnt signaling cascade.

    Science.gov (United States)

    Vanella, Luca; Sodhi, Komal; Kim, Dong Hyun; Puri, Nitin; Maheshwari, Mani; Hinds, Terry D; Bellner, Lars; Goldstein, Dov; Peterson, Stephen J; Shapiro, Joseph I; Abraham, Nader G

    2013-03-12

    Heme oxygenase (HO), a major cytoprotective enzyme, attenuates oxidative stress and obesity. The canonical Wnt signaling cascade plays a pivotal role in the regulation of adipogenesis. The present study examined the interplay between HO-1and the Wnt canonical pathway in the modulation of adipogenesis in mesenchymal stem cell (MSC)-derived adipocytes. To verify the role of HO-1 in generating small healthy adipocytes, cobalt protoporphyrin (CoPP), inducer of HO-1, was used during adipocyte differentiation. Lipid accumulation was measured by Oil red O staining and lipid droplet size was measured by BODIPY staining. During adipogenesis in vitro, differentiating pre-adipocytes display transient increases in the expression of genes involved in canonical Wnt signaling cascade. Increased levels of HO-1 expression and HO activity resulted in elevated levels of β-catenin, pGSK3β, Wnt10b, Pref-1, and shh along with increased levels of adiponectin (P reduction in C/EBPα, PPARγ, Peg-1/Mest, aP2, CD36 expression and lipid accumulation (P adipocyte differentiation suggesting that the HO-1 mediated increase in Wnt10b can modulate the adipocyte phenotype by regulating the transcriptional factors that play a role in adipogenesis. This is evidenced by a decrease in lipid accumulation and inflammatory cytokine levels, increased adiponectin levels and elevation of the expression of genes of the canonical Wnt signaling cascade.

  3. Nitric oxide production upregulates Wnt/β-catenin signaling by inhibiting Dickkopf-1.

    Science.gov (United States)

    Du, Qiang; Zhang, Xinglu; Liu, Quan; Zhang, Xianghong; Bartels, Christian E; Geller, David A

    2013-11-01

    Nitric oxide signaling plays complex roles in carcinogenesis, in part, due to incomplete mechanistic understanding. In this study, we investigated our discovery of an inverse correlation in the expression of the inducible nitric oxide synthase (iNOS) and the Wnt/β-catenin regulator Dickkopf-1 (DKK1) in human cancer. In human tumors and animal models, induced nitric oxide synthesis increased Wnt/β-catenin signaling by negatively regulating DKK1 gene expression. Human iNOS (hiNOS) and DKK1 gene expression were inversely correlated in primary human colon and breast cancers, and in intestinal adenomas from Min (Apc(min/+)) mice. Nitric oxide production by various routes was sufficient to decrease constitutive DKK1 expression, increasing Wnt/β-catenin signaling in colon and breast cancer cells and primary human hepatocytes, thereby activating the transcription of Wnt target genes. This effect could be reversed by RNA interference-mediated silencing of iNOS or treatment with iNOS inhibitors, which restored DKK1 expression and its inhibitory effect on Wnt signaling. Taken together, our results identify a previously unrecognized mechanism through which the nitric oxide pathway promotes cancer by unleashing Wnt/β-catenin signaling. These findings further the evidence that nitric oxide promotes human cancer and deepens insights in the complex control Wnt/β-catenin signaling during carcinogenesis.

  4. Expression profile and function of Wnt signaling mechanisms in malignant mesothelioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Simon A., E-mail: s.fox@curtin.edu.au [Molecular Pharmacology Laboratory, School of Pharmacy, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA (Australia); Richards, Alex K.; Kusumah, Ivonne; Perumal, Vanathi [Molecular Pharmacology Laboratory, School of Pharmacy, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA (Australia); Bolitho, Erin M. [Western Australian Institute for Medical Research, The University of Western Australia Centre for Medical Research, Perth, WA (Australia); Mutsaers, Steven E. [Lung Institute of Western Australia, Centre for Asthma Allergy and Respiratory Research, University of Western Australia, Nedlands (Australia); Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology, University of Western Australia and Western Australian Institute for Medical Research, Nedlands (Australia); Dharmarajan, Arun M. [School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA (Australia)

    2013-10-11

    Highlights: •Expression profile of Wnt pathway related genes in mesothelioma cells. •Differential expression of key Wnt pathway molecules and regulators. •Wnt3a stimulated mesothelioma growth whereas sFRP4 was inhibitory. •Targeting β-Catenin can sensitise mesothelioma cells to cytotoxic drugs. -- Abstract: Malignant mesothelioma (MM) is an uncommon and particularly aggressive cancer associated with asbestos exposure, which currently presents an intractable clinical challenge. Wnt signaling has been reported to play a role in the neoplastic properties of mesothelioma cells but has not been investigated in detail in this cancer. We surveyed expression of Wnts, their receptors, and other key molecules in this pathway in well established in vitro mesothelioma models in comparison with primary mesothelial cultures. We also tested the biological response of MM cell lines to exogenous Wnt and secreted regulators, as well as targeting β-catenin. We detected frequent expression of Wnt3 and Wnt5a, as well as Fzd 2, 4 and 6. The mRNA of Wnt4, Fzd3, sFRP4, APC and axin2 were downregulated in MM relative to mesothelial cells while LEF1 was overexpressed in MM. Functionally, we observed that Wnt3a stimulated MM proliferation while sFRP4 was inhibitory. Furthermore, directly targeting β-catenin expression could sensitise MM cells to cytotoxic drugs. These results provide evidence for altered expression of a number of Wnt/Fzd signaling molecules in MM. Modulation of Wnt signaling in MM may prove a means of targeting proliferation and drug resistance in this cancer.

  5. Wnt/β-catenin Signaling in Normal and Cancer Stem Cells

    Directory of Open Access Journals (Sweden)

    Kenneth C. Valkenburg

    2011-04-01

    Full Text Available The ability of Wnt ligands to initiate a signaling cascade that results in cytoplasmic stabilization of, and nuclear localization of, β-catenin underlies their ability to regulate progenitor cell differentiation. In this review, we will summarize the current knowledge of the mechanisms underlying Wnt/β-catenin signaling and how the pathway regulates normal differentiation of stem cells in the intestine, mammary gland, and prostate. We will also discuss how dysregulation of the pathway is associated with putative cancer stem cells and the potential therapeutic implications of regulating Wnt signaling.

  6. Genomic insights into Wnt signaling in an early diverging metazoan, the ctenophore Mnemiopsis leidyi

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    Pang Kevin

    2010-10-01

    Full Text Available Abstract Background Intercellular signaling pathways are a fundamental component of the integrating cellular behavior required for the evolution of multicellularity. The genomes of three of the four early branching animal phyla (Cnidaria, Placozoa and Porifera have been surveyed for key components, but not the fourth (Ctenophora. Genomic data from ctenophores could be particularly relevant, as ctenophores have been proposed to be one of the earliest branching metazoan phyla. Results A preliminary assembly of the lobate ctenophore Mnemiopsis leidyi genome generated using next-generation sequencing technologies were searched for components of a developmentally important signaling pathway, the Wnt/β-catenin pathway. Molecular phylogenetic analysis shows four distinct Wnt ligands (MlWnt6, MlWnt9, MlWntA and MlWntX, and most, but not all components of the receptor and intracellular signaling pathway were detected. In situ hybridization of the four Wnt ligands showed that they are expressed in discrete regions associated with the aboral pole, tentacle apparati and apical organ. Conclusions Ctenophores show a minimal (but not obviously simple complement of Wnt signaling components. Furthermore, it is difficult to compare the Mnemiopsis Wnt expression patterns with those of other metazoans. mRNA expression of Wnt pathway components appears later in development than expected, and zygotic gene expression does not appear to play a role in early axis specification. Notably absent in the Mnemiopsis genome are most major secreted antagonists, which suggests that complex regulation of this secreted signaling pathway probably evolved later in animal evolution.

  7. Modulation of COUP-TF expression in a cnidarian by ectopic Wnt signalling and allorecognition.

    Directory of Open Access Journals (Sweden)

    David J Duffy

    Full Text Available BACKGROUND: COUP transcription factors are required for the regulation of gene expression underlying development, differentiation, and homeostasis. They have an evolutionarily conserved function, being a known marker for neurogenesis from cnidarians to vertebrates. A homologue of this gene was shown previously to be a neuronal and nematocyte differentiation marker in Hydra. However, COUP-TFs had not previously been studied in a colonial cnidarian. METHODOLOGY/PRINCIPAL FINDINGS: We cloned a COUP-TF homologue from the colonial marine cnidarian Hydractinia echinata. Expression of the gene was analysed during normal development, allorecognition events and ectopic Wnt activation, using in situ hybridisation and quantitative PCR. During normal Hydractinia development, the gene was first expressed in post-gastrula stages. It was undetectable in larvae, and its mRNA was present again in putative differentiating neurons and nematocytes in post-metamorphic stages. Global activation of canonical Wnt signalling in adult animals resulted in the upregulation of COUP-TF. We also monitored a strong COUP-TF upregulation in stolons undergoing allogeneic interactions. COUP-TF mRNA was most concentrated in the tissues that contacted allogeneic, non-self tissues, and decreased in a gradient away from the contact area. Interestingly, the gene was transiently upregulated during initial contact of self stolons, but dissipated rapidly following self recognition, while in non-self contacts high expression levels were maintained. CONCLUSIONS/SIGNIFICANCE: We conclude that COUP-TF is likely involved in neuronal/nematocyte differentiation in a variety of contexts. This has now been shown to include allorecognition, where COUP-TF is thought to have been co-opted to mediate allorejection by recruiting stinging cells that are the effectors of cytotoxic rejection of allogeneic tissue. Our findings that Wnt activation upregulates COUP-TF expression suggests that Wnts' role in

  8. Activation of Wnt/beta-catenin signaling increases insulin sensitivity through a reciprocal regulation of Wnt10b and SREBP-1c in skeletal muscle cells.

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    Mounira Abiola

    2009-12-01

    Full Text Available Intramyocellular lipid accumulation is strongly related to insulin resistance in humans, and we have shown that high glucose concentration induced de novo lipogenesis and insulin resistance in murin muscle cells. Alterations in Wnt signaling impact the balance between myogenic and adipogenic programs in myoblasts, partly due to the decrease of Wnt10b protein. As recent studies point towards a role for Wnt signaling in the pathogenesis of type 2 diabetes, we hypothesized that activation of Wnt signaling could play a crucial role in muscle insulin sensitivity.Here we demonstrate that SREBP-1c and Wnt10b display inverse expression patterns during muscle ontogenesis and regeneration, as well as during satellite cells differentiation. The Wnt/beta-catenin pathway was reactivated in contracting myotubes using siRNA mediated SREBP-1 knockdown, Wnt10b over-expression or inhibition of GSK-3beta, whereas Wnt signaling was inhibited in myoblasts through silencing of Wnt10b. SREBP-1 knockdown was sufficient to induce Wnt10b protein expression in contracting myotubes and to activate the Wnt/beta-catenin pathway. Conversely, silencing Wnt10b in myoblasts induced SREBP-1c protein expression, suggesting a reciprocal regulation. Stimulation of the Wnt/beta-catenin pathway i drastically decreased SREBP-1c protein and intramyocellular lipid deposition in myotubes; ii increased basal glucose transport in both insulin-sensitive and insulin-resistant myotubes through a differential activation of Akt and AMPK pathways; iii restored insulin sensitivity in insulin-resistant myotubes.We conclude that activation of Wnt/beta-catenin signaling in skeletal muscle cells improved insulin sensitivity by i decreasing intramyocellular lipid deposition through downregulation of SREBP-1c; ii increasing insulin effects through a differential activation of the Akt/PKB and AMPK pathways; iii inhibiting the MAPK pathway. A crosstalk between these pathways and Wnt/beta-catenin signaling

  9. Stem cell signaling. An integral program for tissue renewal and regeneration : Wnt signaling and stem cell control

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    Clevers, Hans; Loh, Kyle M; Nusse, Roel

    2014-01-01

    Stem cells fuel tissue development, renewal, and regeneration, and these activities are controlled by the local stem cell microenvironment, the "niche." Wnt signals emanating from the niche can act as self-renewal factors for stem cells in multiple mammalian tissues. Wnt proteins are lipid-modified,

  10. Negative feedback regulation of Wnt4 signaling by EAF1 and EAF2/U19.

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    Xiaoyang Wan

    Full Text Available Previous studies indicated that EAF (ELL-associated factor family members, EAF1 and EAF2/U19, play a role in cancer and embryogenesis. For example, EAF2/U19 may serve as a tumor suppressor in prostate cancer. At the same time, EAF2/U19 is a downstream factor in the non-canonical Wnt 4 signaling pathway required for eye development in Xenopus laevis, and along with EAF1, contributes to convergence and extension movements in zebrafish embryos through Wnt maintenance. Here, we used zebrafish embryos and mammalian cells to show that both EAF1 and EAF2/U19 were up-regulated by Wnt4 (Wnt4a. Furthermore, we found that EAF1 and EAF2/U19 suppressed Wnt4 expression by directly binding to the Wnt4 promoter as seen in chromatin immunoprecipitation assays. These findings indicate that an auto-regulatory negative feedback loop occurs between Wnt4 and the EAF family, which is conserved between zebrafish and mammalian. The rescue experiments in zebrafish embryos showed that early embryonic development required the maintenance of the appropriate levels of Wnt4a through the feedback loop. Others have demonstrated that the tumor suppressors p63, p73 and WT1 positively regulate Wnt4 expression while p21 has the opposite effect, suggesting that maintenance of appropriate Wnt4 expression may also be critical for adult tissue homeostasis and prevention against tumor initiation. Thus, the auto-regulatory negative feedback loop that controls expression of Wnt4 and EAF proteins may play an important role in both embryonic development and tumor suppression. Our findings provide the first convincing line of evidence that EAF and Wnt4 form an auto-regulatory negative feedback loop in vivo.

  11. Wnt5a signaling is a substantial constituent in bone morphogenetic protein-2-mediated osteoblastogenesis

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    Nemoto, Eiji, E-mail: e-nemoto@dent.tohoku.ac.jp [Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai 980-8575 (Japan); Ebe, Yukari; Kanaya, Sousuke [Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai 980-8575 (Japan); Tsuchiya, Masahiro [Department of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai 980-8575 (Japan); Nakamura, Takashi [Department of Pediatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai 980-8575 (Japan); Tamura, Masato [Department of Biochemistry and Molecular Biology, Hokkaido University Graduate School of Dentistry, Sapporo 060-8586 (Japan); Shimauchi, Hidetoshi [Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai 980-8575 (Japan)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Wnt5a is identified in osteoblasts in tibial growth plate and bone marrow. Black-Right-Pointing-Pointer Osteoblastic differentiation is associated with increased expression of Wnt5a/Ror2. Black-Right-Pointing-Pointer Wnt5a/Ror2 signaling is important for BMP-2-mediated osteoblastic differentiation. Black-Right-Pointing-Pointer Wnt5a/Ror2 operates independently of BMP-Smad pathway. -- Abstract: Wnts are secreted glycoproteins that mediate developmental and post-developmental physiology by regulating cellular processes including proliferation, differentiation, and apoptosis through {beta}-catenin-dependent canonical and {beta}-catenin-independent noncanonical pathway. It has been reported that Wnt5a activates noncanonical Wnt signaling through receptor tyrosine kinase-like orphan receptor 2 (Ror2). Although it appears that Wnt5a/Ror2 signaling supports normal bone physiology, the biological significance of noncanonical Wnts in osteogenesis is essentially unknown. In this study, we identified expression of Wnt5a in osteoblasts in the ossification zone of the tibial growth plate as well as bone marrow of the rat tibia as assessed by immunohistochemistry. In addition, we show that osteoblastic differentiation mediated by BMP-2 is associated with increased expression of Wnt5a and Ror2 using cultured pre-osteoblasts, MC3T3-E1 cells. Silencing gene expression of Wnt5a and Ror2 in MC3T3-E1 cells results in suppression of BMP-2-mediated osteoblastic differentiation, suggesting that Wnt5a and Ror2 signaling are of substantial importance for BMP-2-mediated osteoblastic differentiation. BMP-2 stimulation induced phosphorylation of Smad1/5/8 in a similar fashion in both siWnt5a-treated cells and control cells, suggesting that Wnt5a was dispensable for the phosphorylation of Smads by BMP-2. Taken together, our results suggest that Wnt5a/Ror2 signaling appears to be involved in BMP-2-mediated osteoblast differentiation in a Smad independent

  12. Human placental trophoblast invasion and differentiation: a particular focus on Wnt signalling

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    Martin eKnöfler

    2013-09-01

    Full Text Available Wingless ligands, a family of secreted proteins, are critically involved in organ development and tissue homeostasis by ensuring balanced rates of stem cell proliferation, cell death and differentiation. Wnt signalling components also play crucial roles in murine placental development controlling trophoblast lineage determination, chorioallantoic fusion and placental branching morphogenesis. However, the role of the pathway in human placentation, trophoblast development and differentiation is only partly understood. Here, we summarize our present knowledge about Wnt signalling in the human placenta and discuss its potential role in physiological and aberrant trophoblast invasion, gestational diseases and choriocarcinoma formation. Differentiation of proliferative first trimester cytotrophoblasts into invasive extravillous trophoblasts is associated with nuclear recruitment of β-catenin and induction of Wnt-dependent T-cell factor 4 suggesting that canonical Wnt signalling could be important for the formation and function of extravillous trophoblasts. Indeed, activation of the pathway was shown to promote trophoblast invasion in different in vitro trophoblast model systems as well as trophoblast cell fusion. Methylation-mediated silencing of inhibitors of Wnt signalling provided evidence for epigenetic activation of the pathway in placental tissues and choriocarcinoma cells. Similarly, abundant nuclear expression of β-catenin in invasive trophoblasts of complete hydatidiform moles suggested a role for hyper-activated Wnt signalling. In contrast, upregulation of Wnt inhibitors was noticed in placentae of women with preeclampsia, a disease characterized by shallow trophoblast invasion and incomplete spiral artery remodelling. Moreover, changes in Wnt signalling have been observed upon cytomegalovirus infection and in recurrent abortions. In summary, the current literature suggests a critical role of Wnt signalling in physiological and abnormal

  13. Wnt signaling in neuropsychiatric disorders: ties with adult hippocampal neurogenesis and behavior

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    Hussaini, Syed Mohammed Qasim; Choi, Chan-Il; Cho, Chang Hoon; Kim, Hyo Jin; Jun, Heechul; Jang, Mi-Hyeon

    2014-01-01

    In an effort to better understand and treat mental disorders, the Wnt pathway and adult hippocampal neurogenesis have received increased attention in recent years. One is a signaling pathway regulating key aspects of embryonic patterning, cell specification, and adult tissue homeostasis. The other is the generation of newborn neurons in adulthood that integrate into the neural circuit and function in learning and memory, and mood behavior. In this review, we discuss the growing relationship between Wnt signaling-mediated regulation of adult hippocampal neurogenesis as it applies to neuropsychiatric disorders. Evidence suggests dysfunctional Wnt signaling may aberrantly regulate new neuron development and cognitive function. Indeed, altered expression of key Wnt pathway components are observed in the hippocampus of patients suffering from neuropsychiatric disorders. Clinically-utilized mood stabilizers also proceed through modulation of Wnt signaling in the hippocampus, while Wnt pathway antagonists can regulate the antidepressant response. Here, we review the role of Wnt signaling in disease etiology and pathogenesis, regulation of adult neurogenesis and behavior, and the therapeutic targeting of disease symptoms. PMID:25263701

  14. Activation of Wnt/β-catenin/GSK3β signaling during the development of diabetic cardiomyopathy.

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    Xi, Xiao-Hui; Wang, Yan; Li, Jun; Wang, Fu-Wen; Tian, Gui-Hong; Yin, Mao-Shan; Mu, Yan-Ling; Chong, Zhao-Zhong

    2015-01-01

    As Wnt/β-catenin/glycogen synthase kinase 3β (GSK3β) signaling has been implicated in myocardial injury and diabetic cardiomyopathy (DCM) is a major part of diabetic cardiovascular complications, we therefore investigated the alterations of Wnt/β-catenin/GSK3β signaling during the development of DCM. The rat model of diabetes mellitus (DM) was established using a single intraperitoneal injection of streptozotocin (STZ, 60 mg/kg). The alterations of Wnt/β-catenin/GSK3β signaling were determined 4, 8, and 12 weeks following DM using Western blotting, immunohistochemistry, and quantitative real-time reverse transcriptase polymerase chain reaction. Cardiac pathology changes were evaluated using hematoxylin and eosin, Masson trichromatic, and terminal dUTP nick-end labeling staining. Histological analyses revealed that DM induced significant myocardial injury and progressive cardiomyocyte apoptosis. The protein and mRNA levels of Wnt2, β-catenin, and c-Myc were progressively increased 4, 8, and 12 weeks following DM. The expression of T-cell factor 4 and phosphorylated of GSK3β on Ser9 were progressively increased. However, the expression of the endogenous Wnt inhibitor Dickkopf-1 was increased after STZ injection and then decreased as DCM developed. Wnt/β-catenin/GSK3β signaling pathway is activated in the development of DCM. Further investigation into the role of Wnt signaling during DCM will functionally find novel therapeutic target for DCM. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Suppression of Wnt Signaling and Osteogenic Changes in Vascular Smooth Muscle Cells by Eicosapentaenoic Acid

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    Yukihiro Saito

    2017-08-01

    Full Text Available Vascular medial calcification is often observed in patients with arteriosclerosis. It is also associated with systolic hypertension, wide pulse pressure, and fluctuation of blood pressure, which results in cardiovascular events. Eicosapentaenoic acid (EPA has been shown to suppress vascular calcification in previous animal experiments. We investigated the inhibitory effects of EPA on Wnt signaling, which is one of the important signaling pathways involved in vascular calcification. Intake of food containing 5% EPA resulted in upregulation of the mRNA expression of Klotho, an intrinsic inhibitor of Wnt signaling, in the kidneys of wild-type mice. Expression levels of β-catenin, an intracellular signal transducer in the Wnt signaling pathway, were increased in the aortas of Klotho mutant (kl/kl mice compared to the levels in the aortas of wild-type mice. Wnt3a or BIO, a GSK-3 inhibitor that activates β-catenin signaling, upregulated mRNA levels of AXIN2 and LEF1, Wnt signaling marker genes, and RUNX2 and BMP4, early osteogenic genes, in human aorta smooth muscle cells. EPA suppressed the upregulation of AXIN2 and BMP4. The effect of EPA was cancelled by T0070907, a PPARγ inhibitor. The results suggested that EPA could suppress vascular calcification via the inhibition of Wnt signaling in osteogenic vascular smooth muscle cells via PPARγ activation.

  16. Wnt signaling in regulation of biological functions of the nurse cell harboring Trichinella spp.

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    Dabrowska, Magdalena; Skoneczny, Marek; Zielinski, Zbigniew; Rode, Wojciech

    2016-09-02

    The nurse cell (NC) constitutes in mammalian skeletal muscles a confined intracellular niche to support the metabolic needs of muscle larvae of Trichinella spp. encapsulating species. The main biological functions of NC were identified as hypermitogenic growth arrest and pro-inflammatory phenotype, both inferred to depend on AP-1 (activator protein 1) transcription factor. Since those functions, as well as AP-1 activity, are known to be regulated among other pathways, also by Wnt (Wingless-Type of Mouse Mammary Tumor Virus Integration Site) signaling, transcription profiling of molecules participating in Wnt signaling cascades in NC, was performed. Wnt signaling-involved gene expression level was measured by quantitative RT-PCR approach with the use of Qiagen RT(2) Profiler PCR Arrays and complemented by that obtained by searching microarray data sets characterizing NC transcriptome. The genes involved in inhibition of canonical Wnt/β-catenin signaling cascade as well as leading to β-catenin degradation were found expressed in NC at high level, indicating inhibition of this cascade activity. High expression in NC of genes transmitting the signal of Wnt non-canonical signaling cascades leading to activation of AP-1 transcription factor, points to predominant role of non-canonical Wnt signaling in a long term maintenance of NC biological functions. Canonical Wnt/β-catenin signaling cascade is postulated to play a role at the early stages of NC formation when muscle regeneration process is triggered. Following mis-differentiation of infected myofiber and setting of NC functional specificity, are inferred to be controlled among other pathways, by Wnt non-canonical signaling cascades.

  17. Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination.

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    Yuna Kim

    2006-06-01

    Full Text Available The genes encoding members of the wingless-related MMTV integration site (WNT and fibroblast growth factor (FGF families coordinate growth, morphogenesis, and differentiation in many fields of cells during development. In the mouse, Fgf9 and Wnt4 are expressed in gonads of both sexes prior to sex determination. Loss of Fgf9 leads to XY sex reversal, whereas loss of Wnt4 results in partial testis development in XX gonads. However, the relationship between these signals and the male sex-determining gene, Sry, was unknown. We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9 and WNT4 act as opposing signals to regulate sex determination. In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway. Surprisingly, loss of Wnt4 in XX gonads is sufficient to up-regulate Fgf9 and Sox9 in the absence of Sry. These data suggest that the fate of the gonad is controlled by antagonism between Fgf9 and Wnt4. The role of the male sex-determining switch--Sry in the case of mammals--is to tip the balance between these underlying patterning signals. In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways.

  18. Epsin is required for Dishevelled stability and Wnt signaling activation in colon cancer development

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    Chang, Baojun; Tessneer, Kandice L.; McManus, John; Liu, Xiaolei; Hahn, Scott; Pasula, Satish; Wu, Hao; Song, Hoogeun; Chen, Yiyuan; Cai, Xiaofeng; Dong, Yunzhou; Brophy, Megan L.; Rahman, Ruby; Ma, Jian-Xing; Xia, Lijun; Chen, Hong

    2015-01-01

    Uncontrolled canonical Wnt signaling supports colon epithelial tumor expansion and malignant transformation. Understanding the regulatory mechanisms involved is crucial for elucidating the pathogenesis of and will provide new therapeutic targets for colon cancer. Epsins are ubiquitin-binding adaptor proteins upregulated in several human cancers; however, epsins’ involvement in colon cancer is unknown. Here we show that loss of intestinal epithelial epsins protects against colon cancer by significantly reducing the stability of the crucial Wnt signaling effector, dishevelled (Dvl2), and impairing Wnt signaling. Consistently, epsins and Dvl2 are correspondingly upregulated in colon cancer. Mechanistically, epsin binds Dvl2 via its epsin N-terminal homology domain and ubiquitin-interacting motifs and prohibits Dvl2 polyubiquitination and degradation. Our findings reveal an unconventional role for epsins in stabilizing Dvl2 and potentiating Wnt signaling in colon cancer cells to ensure robust colon cancer progression. Epsins’ pro-carcinogenic role suggests they are potential therapeutic targets to combat colon cancer. PMID:25871009

  19. Wnt signaling is involved in human articular chondrocyte de-differentiation in vitro

    NARCIS (Netherlands)

    Sassi, N.; Laadhar, L.; Allouche, M.; Zandieh-Doulabi, B.; Hamdoun, M.; Klein-Nulend, J.; Makni, S.; Sellami, S.

    2014-01-01

    Osteoarthritis is the most prevalent form of arthritis in the world. Certain signaling pathways, such as the wnt pathway, are involved in cartilage pathology. Osteoarthritic chondrocytes undergo morphological and biochemical changes that lead to chondrocyte de-differentiation. We investigated

  20. The Mingle-Mangle of Wnt Signaling and Extracellular Vesicles: Functional Implications for Heart Research

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    Julia Christina Gross

    2018-02-01

    Full Text Available Wnt signaling is an important pathway in health and disease and a key regulator of stem cell maintenance, differentiation, and proliferation. During heart development, Wnt signaling controls specification, proliferation and differentiation of cardiovascular cells. In this regard, the role of activated Wnt signaling in cardiogenesis is well defined. However, the knowledge about signaling transmission has been challenged. Recently, the packaging of hydrophobic Wnt proteins on extracellular vesicles (EVs has emerged as a mechanism to facilitate their extracellular spreading and their functioning as morphogens. EVs spread systemically and therefore can have pleiotropic effects on very different cell types. They are heavily studied in tumor biology where they affect tumor growth and vascularization and can serve as biomarkers in liquid biopsies. In this review we will highlight recent discoveries of factors involved in the release of Wnts on EVs and its potential implications in the communication between physiological and pathological heart cells.

  1. Abnormal WNT5A Signaling Causes Mandibular Hypoplasia in Robinow Syndrome.

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    Hosseini-Farahabadi, S; Gignac, S J; Danescu, A; Fu, K; Richman, J M

    2017-10-01

    The study of rare genetic diseases provides valuable insights into human gene function. Here, we investigate dominant Robinow syndrome (RS), which affects the WNT5A signaling pathway. Autosomal dominant RS is caused by missense mutations in WNT5A or nonsense mutations in the adaptor protein DVL1 or DVL3. The recessive form of the disease is caused by loss-of-function mutations in the receptor ROR2. RS is characterized by hypertelorism, midface, and mandibular hypoplasia. Here, we focus on the missense mutations in WNT5A, since the impact on function is difficult to predict from in silico analysis. We used chicken embryo to express wild-type or 2 mutant versions of human WNT5A in the mandible and then examined the morphologic, cellular, and molecular effects. The 3 experimental viruses-wt WNT5A, WNT5AC83S, or WNT5AC182R-all caused shortening of the mandible on the injected side as compared with GFP controls. Although the phenotypes initially appeared similar, we uncovered specific disruption of chondrocyte polarity and shape, inhibition of cell migration, differences in target gene expression, and absence of JNK signaling only in the presence of mutant viruses. In addition, the missense mutations do not appear to block receptor binding, since in paracrine experiments, the mutant protein inhibits cell migration. In this study, we ruled out a straightforward gain or loss of function caused by the WNT5A missense mutations. Instead, the mutations are likely redirecting WNT signaling away from JNK-PCP toward other noncanonical pathways. We conclude that in RS, WNT5A missense mutations have dominant neomorphic effects that interfere with the function of the wild-type protein.

  2. Understanding and Targeting the Wnt/β-Catenin Signaling Pathway in Chronic Leukemia

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    S. Thanendrarajan

    2011-01-01

    Full Text Available It has been revealed that the Wnt/β-catenin signaling pathway plays an important role in the development of solid tumors and hematological malignancies, particularly in B-cell neoplasia and leukemia. In the last decade there have been made experimental approaches targeting the Wnt pathway in chronic leukemia. In this paper we provide an overview about the current state of knowledge regarding the Wnt/β-catenin signaling pathway in chronic leukemia with special focus on therapeutic options and strategies.

  3. Wnt/β-catenin signaling modulates human airway sensitization induced by β2-adrenoceptor stimulation.

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    Christophe Faisy

    Full Text Available BACKGROUND: Regular use of β2-agonists may enhance non-specific airway responsiveness. The wingless/integrated (Wnt signaling pathways are responsible for several cellular processes, including airway inflammation and remodeling while cAMP-PKA cascade can activate the Wnt signaling. We aimed to investigate whether the Wnt signaling pathways are involved in the bronchial hyperresponsiveness induced by prolonged exposure to β2-adrenoceptor agonists in human isolated airways. METHODS: Bronchi were surgically removed from 44 thoracic surgery patients. After preparation, bronchial rings and primary cultures of bronchial epithelial cells were incubated with fenoterol (0.1 µM, 15 hours, 37 °C, a β2-agonist with high intrinsic efficacy. The effects of inhibitors/blockers of Wnt signaling on the fenoterol-induced airway sensitization were examined and the impact of fenoterol exposure on the mRNA expression of genes interacting with Wnt signaling or cAMP-PKA cascade was assessed in complete bronchi and in cultured epithelial cells. RESULTS: Compared to paired controls, fenoterol-sensitization was abolished by inhibition/blockage of the Wnt/β-catenin signaling, especially the cell-surface LRP5/6 co-receptors or Fzd receptors (1 µM SFRP1 or 1 µM DKK1 and the nuclear recruitment of TCF/LEF transcriptions factors (0.3 µM FH535. Wnt proteins secretion did not seem to be involved in the fenoterol-induced sensitization since the mRNA expression of Wnt remained low after fenoterol exposure and the inactivator of Wnt secretion (1 µM IWP2 had no effect on the fenoterol-sensitization. Fenoterol exposure did not change the mRNA expression of genes regulating Wnt signaling or cAMP-PKA cascade. CONCLUSIONS: Collectively, our pharmacological investigations indicate that fenoterol-sensitization is modulated by the inhibition/blockage of canonical Wnt/β-catenin pathway, suggesting a phenomenon of biased agonism in connection with the β2-adrenoceptor stimulation

  4. Metastasis-associated kinase modulates Wnt signaling to regulate brain patterning and morphogenesis

    OpenAIRE

    Kibardin, Alexey; Ossipova, Olga; Sokol, Sergei Y.

    2006-01-01

    Wnt signaling is a major pathway regulating cell fate determination, cell proliferation and cell movements in vertebrate embryos. Distinct branches of this pathway activate β-catenin/TCF target genes and modulate morphogenetic movements in embryonic tissues by reorganizing the cytoskeleton. The selection of different molecular targets in the pathway is driven by multiple phosphorylation events. Here, we report that metastasis-associated kinase (MAK) is a novel regulator of Wnt signaling durin...

  5. The involvement of lethal giant larvae and Wnt signaling in bottle cell formation in Xenopus embryos.

    Science.gov (United States)

    Choi, Sun-Cheol; Sokol, Sergei Y

    2009-12-01

    Lethal giant larvae (Lgl) plays a critical role in establishment of cell polarity in epithelial cells. While Frizzled/Dsh signaling has been implicated in the regulation of the localization and activity of Lgl, it remains unclear whether specific Wnt ligands are involved. Here we show that Wnt5a triggers the release of Lgl from the cell cortex into the cytoplasm with the concomitant decrease in Lgl stability. The observed changes in Lgl localization were independent of atypical PKC (aPKC), which is known to influence Lgl distribution. In ectodermal cells, both Wnt5a and Lgl triggered morphological and molecular changes characteristic of apical constriction, whereas depletion of their functions prevented endogenous and ectopic bottle cell formation. Furthermore, Lgl RNA partially rescued bottle cell formation in embryos injected with a dominant negative Wnt5a construct. These results suggest a molecular link between Wnt5a and Lgl that is essential for apical constriction during vertebrate gastrulation.

  6. Resveratrol augments the canonical Wnt signaling pathway in promoting osteoblastic differentiation of multipotent mesenchymal cells

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    Zhou, Haibin; Shang, Linshan; Li, Xi; Zhang, Xiyu; Gao, Guimin; Guo, Chenhong; Chen, Bingxi; Liu, Qiji [Key Laboratory of Experimental Teratology, MOE, Institute of Molecular Medicine and Genetics, Shandong University, 44 Wen Hua Xi Lu, Jinan, Shandong 250012 (China); Gong, Yaoqin, E-mail: yxg8@sdu.edu.cn [Key Laboratory of Experimental Teratology, MOE, Institute of Molecular Medicine and Genetics, Shandong University, 44 Wen Hua Xi Lu, Jinan, Shandong 250012 (China); Shao, Changshun, E-mail: shao@biology.rutgers.edu [Key Laboratory of Experimental Teratology, MOE, Institute of Molecular Medicine and Genetics, Shandong University, 44 Wen Hua Xi Lu, Jinan, Shandong 250012 (China); Department of Genetics, Rutgers University, Piscataway, NJ 08854 (United States)

    2009-10-15

    Resveratrol has been shown to possess many health-benefiting effects, including the promotion of bone formation. In this report we investigated the mechanism by which resveratrol promotes osteoblastic differentiation from pluripotent mesenchymal cells. Since Wnt signaling is well documented to induce osteoblastogenesis and bone formation, we characterized the factors involved in Wnt signaling in response to resveratrol treatment. Resveratrol treatment of mesenchymal cells led to an increase in stabilization and nuclear accumulation of {beta}-catenin dose-dependently and time-dependently. As a consequence of the increased nuclear accumulation of {beta}-catenin, the ability to activate transcription of {beta}-catenin-TCF/LEF target genes that are required for osteoblastic differentiation was upregulated. However, resveratrol did not affect the initial step of the Wnt signaling pathway, as resveratrol was as effective in upregulating the activity of {beta}-catenin in cells in which Lrp5 was knocked down as in control cells. In addition, while conditioned medium enriched in Wnt signaling antagonist Dkk1 was able to inhibit Wnt3a-induced {beta}-catenin upregulation, this inhibitory effect can be abolished in resveratrol-treated cells. Furthermore, we showed that the level of glycogen synthase kinase 3{beta} (GSK-3{beta}), which phosphorylates and destabilizes {beta}-catenin, was reduced in response to resveratrol treatment. The phosphorylation of GSK-3{beta} requires extracellular signal-regulated kinase (ERK)1/2. Together, our data indicate that resveratrol promotes osteoblastogenesis and bone formation by augmenting Wnt signaling.

  7. JNK signalling is necessary for a Wnt- and stem cell-dependent regeneration programme

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    Tejada-Romero, Belen; Carter, Jean-Michel; Mihaylova, Yuliana; Neumann, Bjoern; Aboobaker, A. Aziz

    2015-01-01

    Regeneration involves the integration of new and old tissues in the context of an adult life history. It is clear that the core conserved signalling pathways that orchestrate development also play central roles in regeneration, and further study of conserved signalling pathways is required. Here we have studied the role of the conserved JNK signalling cascade during planarian regeneration. Abrogation of JNK signalling by RNAi or pharmacological inhibition blocks posterior regeneration and animals fail to express posterior markers. While the early injury-induced expression of polarity markers is unaffected, the later stem cell-dependent phase of posterior Wnt expression is not established. This defect can be rescued by overactivation of the Hh or Wnt signalling pathway to promote posterior Wnt activity. Together, our data suggest that JNK signalling is required to establish stem cell-dependent Wnt expression after posterior injury. Given that Jun is known to be required in vertebrates for the expression of Wnt and Wnt target genes, we propose that this interaction may be conserved and is an instructive part of planarian posterior regeneration. PMID:26062938

  8. Increased glutamine catabolism mediates bone anabolism in response to WNT signaling.

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    Karner, Courtney M; Esen, Emel; Okunade, Adewole L; Patterson, Bruce W; Long, Fanxin

    2015-02-01

    WNT signaling stimulates bone formation by increasing both the number of osteoblasts and their protein-synthesis activity. It is not clear how WNT augments the capacity of osteoblast progenitors to meet the increased energetic and synthetic needs associated with mature osteoblasts. Here, in cultured osteoblast progenitors, we determined that WNT stimulates glutamine catabolism through the tricarboxylic acid (TCA) cycle and consequently lowers intracellular glutamine levels. The WNT-induced reduction of glutamine concentration triggered a general control nonderepressible 2-mediated (GCN2-mediated) integrated stress response (ISR) that stimulated expression of genes responsible for amino acid supply, transfer RNA (tRNA) aminoacylation, and protein folding. WNT-induced glutamine catabolism and ISR were β-catenin independent, but required mammalian target of rapamycin complex 1 (mTORC1) activation. In a hyperactive WNT signaling mouse model of human osteosclerosis, inhibition of glutamine catabolism or Gcn2 deletion suppressed excessive bone formation. Together, our data indicate that glutamine is both an energy source and a protein-translation rheostat that is responsive to WNT and suggest that manipulation of the glutamine/GCN2 signaling axis may provide a valuable approach for normalizing deranged protein anabolism associated with human diseases.

  9. Wnt/β-catenin signalling pathway mediated aberrant hippocampal neurogenesis in kainic acid-induced epilepsy.

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    Qu, Zhengyi; Su, Fang; Qi, Xueting; Sun, Jianbo; Wang, Hongcai; Qiao, Zhenkui; Zhao, Hong; Zhu, Yulan

    2017-10-01

    Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis with massive neuronal loss and severe gliosis. Aberrant neurogenesis has been shown in the epileptogenesis process of temporal lobe epilepsy. However, the molecular mechanisms underlying aberrant neurogenesis remain unclear. The roles of Wnt signalling cascade have been well established in neurogenesis during multiple aspects. Here, we used kainic acid-induced rat epilepsy model to investigate whether Wnt/β-catenin signalling pathway is involved in the aberrant neurogenesis in temporal lobe epilepsy. Immunostaining and western blotting results showed that the expression levels of β-catenin, Wnt3a, and cyclin D1, the key regulators in Wnt signalling pathway, were up-regulated during acute epilepsy induced by the injection of kainic acids, indicating that Wnt signalling pathway was activated in kainic acid-induced temporal lobe epilepsy. Moreover, BrdU labelling results showed that blockade of the Wnt signalling by knocking down β-catenin attenuated aberrant neurogenesis induced by kainic acids injection. Altogether, Wnt/β-catenin signalling pathway mediated hippocampal neurogenesis during epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy. Temporal lobe epilepsy is a chronic disorder of nerve system, mainly characterized by hippocampal sclerosis. Aberrant neurogenesis has been shown to involve in the epileptogenesis process of temporal lobe epilepsy. In the present study, we discovered that Wnt3a/β-catenin signalling pathway serves as a link between aberrant neurogenesis and underlying remodelling in the hippocampus, leading to temporal lobe epilepsy, which might provide new strategies for clinical treatment of temporal lobe epilepsy. Copyright © 2017 John Wiley & Sons, Ltd.

  10. Modulating Wnt Signaling Rescues Palate Morphogenesis in Pax9 Mutant Mice.

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    Li, C; Lan, Y; Krumlauf, R; Jiang, R

    2017-10-01

    Cleft palate is a common birth defect caused by disruption of palatogenesis during embryonic development. Although mutations disrupting components of the Wnt signaling pathway have been associated with cleft lip and palate in humans and mice, the mechanisms involving canonical Wnt signaling and its regulation in secondary palate development are not well understood. Here, we report that canonical Wnt signaling plays an important role in Pax9-mediated regulation of secondary palate development. We found that cleft palate pathogenesis in Pax9-deficient embryos is accompanied by significantly reduced expression of Axin2, an endogenous target of canonical Wnt signaling, in the developing palatal mesenchyme, particularly in the posterior regions of the palatal shelves. We found that expression of Dkk2, encoding a secreted Wnt antagonist, is significantly increased whereas the levels of active β-catenin protein, the essential transcriptional coactivator of canonical Wnt signaling, is significantly decreased in the posterior regions of the palatal shelves in embryonic day 13.5 Pax9-deficent embryos in comparison with control littermates. We show that small molecule-mediated inhibition of Dickkopf (DKK) activity in utero during palatal shelf morphogenesis partly rescued secondary palate development in Pax9-deficient embryos. Moreover, we found that genetic inactivation of Wise, which is expressed in the developing palatal shelves and encodes another secreted antagonist of canonical Wnt signaling, also rescued palate morphogenesis in Pax9-deficient mice. Furthermore, whereas Pax9del/del embryos exhibit defects in palatal shelf elevation/reorientation and significant reduction in accumulation of hyaluronic acid-a high molecular extracellular matrix glycosaminoglycan implicated in playing an important role in palatal shelf elevation-80% of Pax9del/del;Wise-/- double-mutant mouse embryos exhibit rescued palatal shelf elevation/reorientation, accompanied by restored hyaluronic

  11. Expression of canonical WNT/β-CATENIN signaling components in the developing human lung

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    Zhang Mingfeng

    2012-07-01

    Full Text Available Abstract Background The WNT/β-CATENIN signaling cascade is crucial for the patterning of the early lung morphogenesis in mice, but its role in the developing human lung remains to be determined. In this study, expression patterns of canonical WNT/β-CATENIN signaling components, including WNT ligands (WNT2, WNT7B, receptors ( FZD4, FZD7, LRP5, LRP6, transducers ( DVL2, DVL3, GSK-3β, β-CATENIN, APC, AXIN2, transcription factors ( TCF4, LEF1 and antagonists ( SOSTDC1 were examined in human embryonic lung at 7, 12, 17 and 21 weeks of gestation (W by real-time qRT-PCR and in situ hybridization. Results qRT-PCR analysis showed that some of these components were gradually upregulated, while some were significantly downregulated from the 7 W to the 12 W. However, most components reached a high level at 17 W, with a subsequent decrease at 21 W. In situ hybridization showed that the canonical WNT ligands and receptors were predominantly located in the peripheral epithelium, whereas the canonical WNT signal transducers and transcription factors were not only detected in the respiratory epithelium, but some were also scattered at low levels in the surrounding mesenchyme in the developing human lung. Furthermore, Western blot, qRT-PCR and histological analysis demonstrated that the β-CATENIN-dependent WNT signaling in embryonic human lung was activated in vitro by CHIR 99021 stimulation. Conclusions This study of the expression patterns and in vitro activity of the canonical WNT/β-CATENIN pathways suggests that these components play an essential role in regulation of human lung development.

  12. Attenuated Wnt/β-catenin signalling mediates methotrexate chemotherapy-induced bone loss and marrow adiposity in rats.

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    Georgiou, Kristen R; King, Tristan J; Scherer, Michaela A; Zhou, Hong; Foster, Bruce K; Xian, Cory J

    2012-06-01

    Cancer chemotherapy often causes significant bone loss, marrow adiposity and haematopoietic defects, yet the underlying mechanisms and recovery potential remain unclear. Wnt/β-catenin signalling is integral to the regulation of osteogenesis, adipogenesis and haematopoiesis; using a rat model, the current study investigated roles of this signalling pathway in changes to bone marrow stromal and haematopoietic cell differentiation after chemotherapy with methotrexate (MTX), a commonly used antimetabolite. MTX treatment in rats (5 daily administrations at 0.75 mg/kg) has previously been found to decrease bone volume and increase marrow fat, which was associated with increased osteoclastogenesis in haematopoietic cells and with an osteogenesis to adipogenesis switch in bone marrow stromal cells of treated rats. In the current study, on day 6 after the first MTX dose we found that accompanying these changes as well as a suppressed haematopoietic cellularity but increased granulocyte/macrophage differentiation potential, there was an increase in mRNA expression of Wnt antagonists sFRP-1 and Dkk-1 in bone, a reduction in nuclear β-catenin protein in bone marrow stromal cells, and decreased mRNA levels of β-catenin target genes lef-1, cyclin D1 and survivin, suggesting reduced activation of Wnt/β-catenin signalling in the bone during MTX-induced damage. Concurrent administration of BIO, a GSK-3β inhibitor that stabilises β-catenin, partially abrogated the MTX-induced transient changes in osteogenic/adipogenic commitment, granulocyte/macrophage lineage differentiation and osteoclast number. These findings demonstrate a potentially important role of Wnt/β-catenin signalling in MTX chemotherapy-induced cellular changes to the bone marrow microenvironment. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Non-canonical Wnt signalling modulates the endothelial shear stress flow sensor in vascular remodelling.

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    Franco, Claudio A; Jones, Martin L; Bernabeu, Miguel O; Vion, Anne-Clemence; Barbacena, Pedro; Fan, Jieqing; Mathivet, Thomas; Fonseca, Catarina G; Ragab, Anan; Yamaguchi, Terry P; Coveney, Peter V; Lang, Richard A; Gerhardt, Holger

    2016-02-04

    Endothelial cells respond to molecular and physical forces in development and vascular homeostasis. Deregulation of endothelial responses to flow-induced shear is believed to contribute to many aspects of cardiovascular diseases including atherosclerosis. However, how molecular signals and shear-mediated physical forces integrate to regulate vascular patterning is poorly understood. Here we show that endothelial non-canonical Wnt signalling regulates endothelial sensitivity to shear forces. Loss of Wnt5a/Wnt11 renders endothelial cells more sensitive to shear, resulting in axial polarization and migration against flow at lower shear levels. Integration of flow modelling and polarity analysis in entire vascular networks demonstrates that polarization against flow is achieved differentially in artery, vein, capillaries and the primitive sprouting front. Collectively our data suggest that non-canonical Wnt signalling stabilizes forming vascular networks by reducing endothelial shear sensitivity, thus keeping vessels open under low flow conditions that prevail in the primitive plexus.

  14. EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling

    Directory of Open Access Journals (Sweden)

    Makoto Takeo

    2016-05-01

    Full Text Available Delineating the crosstalk between distinct signaling pathways is key to understanding the diverse and dynamic responses of adult stem cells during tissue regeneration. Here, we demonstrate that the Edn/EdnrB signaling pathway can interact with other signaling pathways to elicit distinct stem cell functions during tissue regeneration. EdnrB signaling promotes proliferation and differentiation of melanocyte stem cells (McSCs, dramatically enhancing the regeneration of hair and epidermal melanocytes. This effect is dependent upon active Wnt signaling that is initiated by Wnt ligand secretion from the hair follicle epithelial niche. Further, this Wnt-dependent EdnrB signaling can rescue the defects in melanocyte regeneration caused by Mc1R loss. This suggests that targeting Edn/EdnrB signaling in McSCs can be a therapeutic approach to promote photoprotective-melanocyte regeneration, which may be useful for those with increased risk of skin cancers due to Mc1R variants.

  15. Modulation of apical constriction by Wnt signaling is required for lung epithelial shape transition.

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    Fumoto, Katsumi; Takigawa-Imamura, Hisako; Sumiyama, Kenta; Kaneiwa, Tomoyuki; Kikuchi, Akira

    2017-01-01

    In lung development, the apically constricted columnar epithelium forms numerous buds during the pseudoglandular stage. Subsequently, these epithelial cells change shape into the flat or cuboidal pneumocytes that form the air sacs during the canalicular and saccular (canalicular-saccular) stages, yet the impact of cell shape on tissue morphogenesis remains unclear. Here, we show that the expression of Wnt components is decreased in the canalicular-saccular stages, and that genetically constitutive activation of Wnt signaling impairs air sac formation by inducing apical constriction in the epithelium as seen in the pseudoglandular stage. Organ culture models also demonstrate that Wnt signaling induces apical constriction through apical actomyosin cytoskeletal organization. Mathematical modeling reveals that apical constriction induces bud formation and that loss of apical constriction is required for the formation of an air sac-like structure. We identify MAP/microtubule affinity-regulating kinase 1 (Mark1) as a downstream molecule of Wnt signaling and show that it is required for apical cytoskeletal organization and bud formation. These results suggest that Wnt signaling is required for bud formation by inducing apical constriction during the pseudoglandular stage, whereas loss of Wnt signaling is necessary for air sac formation in the canalicular-saccular stages. © 2017. Published by The Company of Biologists Ltd.

  16. MnTBAP Inhibits Bleomycin-Induced Pulmonary Fibrosis by Regulating VEGF and Wnt Signaling

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    Venkatadri, Rajkumar; Krishnan V. Iyer, Anand; Ramesh, Vani; Wright, Clayton; Castro, Carlos A.; Yakisich, Juan S.; Azad, Neelam

    2017-01-01

    Cellular oxidative stress is implicated not only in lung injury but also in contributing to the development of pulmonary fibrosis. We demonstrate that a cell-permeable superoxide dismutase (SOD) mimetic and peroxynitrite scavenger, manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) significantly inhibited bleomycin-induced fibrogenic effects both in vitro and in vivo. Further investigation into the underlying mechanisms revealed that MnTBAP targets canonical Wnt and non-canonical Wnt/Ca2+ signaling pathways, both of which were upregulated by bleomycin treatment. The effect of MnTBAP on canonical Wnt signaling was significant in vivo but inconclusive in vitro and the non-canonical Wnt/Ca2+ signaling pathway was observed to be the predominant pathway regulated by MnTBAP in bleomycin-induced pulmonary fibrosis. Furthermore, we show that the inhibitory effects of MnTBAP involve regulation of VEGF which is upstream of the Wnt signaling pathway. Overall, the data show that the superoxide scavenger MnTBAP attenuates bleomycin-induced pulmonary fibrosis by targeting VEGF and Wnt signaling pathways. PMID:27649046

  17. Tyrosine-based signal mediates LRP6 receptor endocytosis and desensitization of Wnt/β-catenin pathway signaling.

    Science.gov (United States)

    Liu, Chia-Chen; Kanekiyo, Takahisa; Roth, Barbara; Bu, Guojun

    2014-10-03

    Wnt/β-catenin signaling orchestrates a number of critical events including cell growth, differentiation, and cell survival during development. Misregulation of this pathway leads to various human diseases, specifically cancers. Endocytosis and phosphorylation of the LDL receptor-related protein 6 (LRP6), an essential co-receptor for Wnt/β-catenin signaling, play a vital role in mediating Wnt/β-catenin signal transduction. However, its regulatory mechanism is not fully understood. In this study, we define the mechanisms by which LRP6 endocytic trafficking regulates Wnt/β-catenin signaling activation. We show that LRP6 mutant with defective tyrosine-based signal in its cytoplasmic tail has an increased cell surface distribution and decreased endocytosis rate. These changes in LRP6 endocytosis coincide with an increased distribution to caveolae, increased phosphorylation, and enhanced Wnt/β-catenin signaling. We further demonstrate that treatment of Wnt3a ligands or blocking the clathrin-mediated endocytosis of LRP6 leads to a redistribution of wild-type receptor to lipid rafts. The LRP6 tyrosine mutant also exhibited an increase in signaling activation in response to Wnt3a stimulation when compared with wild-type LRP6, and this activation is suppressed when caveolae-mediated endocytosis is blocked. Our results reveal molecular mechanisms by which LRP6 endocytosis routes regulate its phosphorylation and the strength of Wnt/β-catenin signaling, and have implications on how this pathway can be modulated in human diseases. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Multiple modes of Lrp4 function in modulation of Wnt/β-catenin signaling during tooth development.

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    Ahn, Youngwook; Sims, Carrie; Murray, Megan J; Kuhlmann, Paige K; Fuentes-Antrás, Jesús; Weatherbee, Scott D; Krumlauf, Robb

    2017-08-01

    During development and homeostasis, precise control of Wnt/β-catenin signaling is in part achieved by secreted and membrane proteins that negatively control activity of the Wnt co-receptors Lrp5 and Lrp6. Lrp4 is related to Lrp5/6 and is implicated in modulation of Wnt/β-catenin signaling, presumably through its ability to bind to the Wise (Sostdc1)/sclerostin (Sost) family of Wnt antagonists. To gain insights into the molecular mechanisms of Lrp4 function in modulating Wnt signaling, we performed an array of genetic analyses in murine tooth development, where Lrp4 and Wise play important roles. We provide genetic evidence that Lrp4 mediates the Wnt inhibitory function of Wise and also modulates Wnt/β-catenin signaling independently of Wise. Chimeric receptor analyses raise the possibility that the Lrp4 extracellular domain interacts with Wnt ligands, as well as the Wnt antagonists. Diverse modes of Lrp4 function are supported by severe tooth phenotypes of mice carrying a human mutation known to abolish Lrp4 binding to Sost. Our data suggest a model whereby Lrp4 modulates Wnt/β-catenin signaling via interaction with Wnt ligands and antagonists in a context-dependent manner. © 2017. Published by The Company of Biologists Ltd.

  19. Activated wnt signaling in stroma contributes to development of pancreatic mucinous cystic neoplasms.

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    Sano, Makoto; Driscoll, David R; De Jesus-Monge, Wilfredo E; Klimstra, David S; Lewis, Brian C

    2014-01-01

    Pancreatic mucinous cystic neoplasm (MCN), a cystic tumor of the pancreas that develops most frequently in women, is a potential precursor to pancreatic ductal adenocarcinoma. MCNs develop primarily in the body and tail of the pancreas and are characterized by the presence of a mucinous epithelium and ovarian-like subepithelial stroma. We investigated the involvement of Wnt signaling in KRAS-mediated pancreatic tumorigenesis and development of MCN in mice, and Wnt activation in human MCN samples. LSL-Kras(G12D), Ptf1a-cre mice were crossed with elastase-tva mice to allow for introduction of genes encoded by the replication-competent avian sarcoma-leukosis virus long-terminal repeat with splice acceptor viruses to pancreatic acinar cells and acinar cell progenitors, postnatally and sporadically. Repeat with splice acceptor viruses that expressed Wnt1 were delivered to the pancreatic epithelium of these mice; pancreatic lesions were analyzed by histopathology and immunohistochemical analyses. We analyzed levels of factors in Wnt signaling pathways in 19 MCN samples from patients. Expression of Wnt1 in the pancreatic acinar cells and acinar cell progenitors of female mice led to development of unilocular or multilocular epithelial cysts in the pancreas body and tail, similar to MCN. The cystic lesions resembled the estrogen receptor- and progesterone receptor-positive ovarian-like stroma of MCN, but lacked the typical mucinous epithelium. Activated Wnt signaling, based on nuclear localization of β-catenin, was detected in the stroma but not cyst epithelium. Wnt signaling to β-catenin was found to be activated in MCN samples from patients, within the ovarian-like stroma, consistent with the findings in mice. Based on studies of mice and pancreatic MCN samples from patients, the canonical Wnt signaling pathway becomes activated and promotes development of the ovarian-like stroma to contribute to formation of MCNs. Copyright © 2014 AGA Institute. Published by Elsevier

  20. Fluoxetine ameliorates cartilage degradation in osteoarthritis by inhibiting Wnt/β-catenin signaling.

    Science.gov (United States)

    Miyamoto, Kentaro; Ohkawara, Bisei; Ito, Mikako; Masuda, Akio; Hirakawa, Akihiro; Sakai, Tadahiro; Hiraiwa, Hideki; Hamada, Takashi; Ishiguro, Naoki; Ohno, Kinji

    2017-01-01

    Abnormal activation of the Wnt/β-catenin signaling is implicated in the osteoarthritis (OA) pathology. We searched for a pre-approved drug that suppresses abnormally activated Wnt/β-catenin signaling and has a potency to reduce joint pathology in OA. We introduced the TOPFlash reporter plasmid into HCS-2/8 human chondrosarcoma cells to estimate the Wnt/β-catenin activity in the presence of 10 μM each compound in a panel of pre-approved drugs. We found that fluoxetine, an antidepressant in the class of selective serotonin reuptake inhibitors (SSRI), down-regulated Wnt/β-catenin signaling in human chondrosarcoma cells. Fluoxetine inhibited both Wnt3A- and LiCl-induced loss of proteoglycans in chondrogenically differentiated ATDC5 cells. Fluoxetine increased expression of Sox9 (the chondrogenic master regulator), and decreased expressions of Axin2 (a marker for Wnt/β-catenin signaling) and Mmp13 (matrix metalloproteinase 13). Fluoxetine suppressed a LiCl-induced increase of total β-catenin and a LiCl-induced decrease of phosphorylated β-catenin in a dose-dependent manner. An in vitro protein-binding assay showed that fluoxetine enhanced binding of β-catenin with Axin1, which is a scaffold protein forming the degradation complex for β-catenin. Fluoxetine suppressed LiCl-induced β-catenin accumulation in human OA chondrocytes. Intraarticular injection of fluoxetine in a rat OA model ameliorated OA progression and suppressed β-catenin accumulation.

  1. Wnt3a upregulates brain-derived insulin by increasing NeuroD1 via Wnt/β-catenin signaling in the hypothalamus.

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    Lee, Jaemeun; Kim, Kyungchan; Yu, Seong-Woon; Kim, Eun-Kyoung

    2016-03-08

    Insulin plays diverse roles in the brain. Although insulin produced by pancreatic β-cells that crosses the blood-brain barrier is a major source of brain insulin, recent studies suggest that insulin is also produced locally within the brain. However, the mechanisms underlying the production of brain-derived insulin (BDI) are not yet known. Here, we examined the effect of Wnt3a on BDI production in a hypothalamic cell line and hypothalamic tissue. In N39 hypothalamic cells, Wnt3a treatment significantly increased the expression of the Ins2 gene, which encodes the insulin isoform predominant in the mouse brain, by activating Wnt/β-catenin signaling. The concentration of insulin was higher in culture medium of Wnt3a-treated cells than in that of untreated cells. Interestingly, neurogenic differentiation 1 (NeuroD1), a target of Wnt/β-catenin signaling and one of transcription factors for insulin, was also induced by Wnt3a treatment in a time- and dose-dependent manner. In addition, the treatment of BIO, a GSK3 inhibitor, also increased the expression of Ins2 and NeuroD1. Knockdown of NeuroD1 by lentiviral shRNAs reduced the basal expression of Ins2 and suppressed Wnt3a-induced Ins2 expression. To confirm the Wnt3a-induced increase in Ins2 expression in vivo, Wnt3a was injected into the hypothalamus of mice. Wnt3a increased the expression of NeuroD1 and Ins2 in the hypothalamus in a manner similar to that observed in vitro. Taken together, these results suggest that BDI production is regulated by the Wnt/β-catenin/NeuroD1 pathway in the hypothalamus. Our findings will help to unravel the regulation of BDI production in the hypothalamus.

  2. Wnt-RhoA signaling pathways in fluoride-treated ameloblast-lineage cells.

    Science.gov (United States)

    Shusterman, Kate; Gibson, Carolyn W; Li, Yong; Healey, Melissa; Peng, Li

    2014-01-01

    This study examined the effect of sodium fluoride (NaF) on the Wnt and RhoA signaling pathways in murine ameloblast-lineage cells (ALCs) to better understand the developmental mechanisms of dental fluorosis. Wnt and Rho pathway activities were investigated when ALCs were treated with 1.5 mM NaF, dickkopf-related protein-1 (Dkk-1), secreted frizzled related-protein-2 (sFRP-2), β-catenin siRNA dominant negative RhoA (RhoA(DN)) plasmid and Y-27632. Wnt pathway activity was investigated via RT-PCR, Western blot and Topflash luciferase assay. The activity of the RhoA pathway was analyzed via Rho pull-down assay and immunoprecipitation. The differentiation of ALCs was analyzed by alkaline phosphatase assay. Western blot and Topflash luciferase assay results verified that both the Wnt and Rho pathways were upregulated by 1.5 mM NaF. Wnt was discovered to be located upstream from the Rho pathway, as confirmed by treatment with Wnt pathway cell receptor inhibitors Dkk-1 and sFRP-2, leading to a decrease in RhoA and ROCK activity. Inhibition of the Rho pathway with RhoA(DN) plasmid and Y-27632 caused upregulation of Wnt pathway activity which could be further increased by 1.5 mM NaF. The increased Wnt pathway activity was found to negatively regulate ALC differentiation. These data suggest that fluoride could induce the cross-talk between Wnt and RhoA signaling pathways, and these responses are predicted to contribute to the development of enamel fluorosis. © 2014 S. Karger AG, Basel.

  3. Wnt-signalling pathways and microRNAs network in carcinogenesis: experimental and bioinformatics approaches.

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    Onyido, Emenike K; Sweeney, Eloise; Nateri, Abdolrahman Shams

    2016-09-02

    Over the past few years, microRNAs (miRNAs) have not only emerged as integral regulators of gene expression at the post-transcriptional level but also respond to signalling molecules to affect cell function(s). miRNAs crosstalk with a variety of the key cellular signalling networks such as Wnt, transforming growth factor-β and Notch, control stem cell activity in maintaining tissue homeostasis, while if dysregulated contributes to the initiation and progression of cancer. Herein, we overview the molecular mechanism(s) underlying the crosstalk between Wnt-signalling components (canonical and non-canonical) and miRNAs, as well as changes in the miRNA/Wnt-signalling components observed in the different forms of cancer. Furthermore, the fundamental understanding of miRNA-mediated regulation of Wnt-signalling pathway and vice versa has been significantly improved by high-throughput genomics and bioinformatics technologies. Whilst, these approaches have identified a number of specific miRNA(s) that function as oncogenes or tumour suppressors, additional analyses will be necessary to fully unravel the links among conserved cellular signalling pathways and miRNAs and their potential associated components in cancer, thereby creating therapeutic avenues against tumours. Hence, we also discuss the current challenges associated with Wnt-signalling/miRNAs complex and the analysis using the biomedical experimental and bioinformatics approaches.

  4. Polarized activation of notum at wounds inhibits Wnt signaling to promote planarian head regeneration

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    Petersen, Christian P.; Reddien, Peter W.

    2011-01-01

    Regeneration requires initiation of programs tailored to the identity of missing parts. Head-versus-tail regeneration in planarians presents a paradigm for study of this phenomenon. Following injury, Wnt signaling promotes tail regeneration. We report that wounding elicits expression of the Wnt inhibitor notum preferentially at anterior-facing wounds. This expression asymmetry occurs at essentially any wound, even if the anterior pole is intact. notum(RNAi) animals regenerate an anterior-faci...

  5. A positive role of cadherin in Wnt/β-catenin signalling during epithelial-mesenchymal transition.

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    Sara Howard

    Full Text Available The Wnt/β-catenin signalling pathway shares a key component, β-catenin, with the cadherin-based adhesion system. The signalling function of β-catenin is conferred by a soluble cytoplasmic pool that is unstable in the absence of a Wnt signal, whilst the adhesion function is based on a cadherin-bound, stable pool at the membrane. The cadherin complex is dynamic, allowing for cell-cell rearrangements such as epithelial-mesenchymal transition (EMT, where the complex turns over through internalisation. Potential interplay between the two pools remains poorly understood, but cadherins are generally considered negative regulators of Wnt signalling because they sequester cytoplasmic β-catenin. Here we explore how cellular changes at EMT affect the signalling capacity of β-catenin using two models of EMT: hepatocyte growth factor (HGF treatment of MDCK cells, and gastrulation in embryonic development. We show that EMT not only provides a pool of signalling-competent β-catenin following internalisation of cadherin, but also significantly facilitates activation of the Wnt pathway in response to both Wnt signals and exogenous β-catenin. We further demonstrate that availability of β-catenin in the cytoplasm does not necessarily correlate with Wnt/β-catenin pathway activity, since blocking endocytosis or depleting endogenous cadherin abolishes pathway activation despite the presence of β-catenin in the cytoplasm. Lastly we present data suggesting that cadherins are required for augmented activation of the Wnt/β-catenin pathway in vivo. This suggests that cadherins play a crucial role in β-catenin-dependent transcription.

  6. Bili inhibits Wnt/beta-catenin signaling by regulating the recruitment of axin to LRP6.

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    Lorna S Kategaya

    Full Text Available BACKGROUND: Insights into how the Frizzled/LRP6 receptor complex receives, transduces and terminates Wnt signals will enhance our understanding of the control of the Wnt/ss-catenin pathway. METHODOLOGY/PRINCIPAL FINDINGS: In pursuit of such insights, we performed a genome-wide RNAi screen in Drosophila cells expressing an activated form of LRP6 and a beta-catenin-responsive reporter. This screen resulted in the identification of Bili, a Band4.1-domain containing protein, as a negative regulator of Wnt/beta-catenin signaling. We found that the expression of Bili in Drosophila embryos and larval imaginal discs significantly overlaps with the expression of Wingless (Wg, the Drosophila Wnt ortholog, which is consistent with a potential function for Bili in the Wg pathway. We then tested the functions of Bili in both invertebrate and vertebrate animal model systems. Loss-of-function studies in Drosophila and zebrafish embryos, as well as human cultured cells, demonstrate that Bili is an evolutionarily conserved antagonist of Wnt/beta-catenin signaling. Mechanistically, we found that Bili exerts its antagonistic effects by inhibiting the recruitment of AXIN to LRP6 required during pathway activation. CONCLUSIONS: These studies identify Bili as an evolutionarily conserved negative regulator of the Wnt/beta-catenin pathway.

  7. Pygopus Maintains Heart Function in Aging Drosophila Independently of Canonical Wnt Signaling

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    Tang, Min; Yuan, Wuzhou; Fan, Xiongwei; Liu, Ming; Bodmer, Rolf; Ocorr, Karen; Wu, Xiushan

    2013-01-01

    Background Heart function declines with age, but the genetic factors underlying such deterioration are largely unknown. Wnt signaling is known to play a role in heart development, but it has not been shown to be important in adult heart function. We have investigated the nuclear adapter protein encoded by pygopus (pygo), which mediates canonical Wnt signaling, for roles in aging-related cardiac dysfunction. Methods and Results Using the Drosophila heart model, we show that cardiac-specific pygo knockdown in adult flies causes a significant (4- to 5-fold) increase in cardiac arrhythmias (Pfunctional and morphological alterations were ameliorated by pygo overexpression. Unexpectedly, knockdown of 2 other Wnt signaling components, β-cat/armadillo or TCF/pangolin, had relatively milder effects on cardiac function. Double-heterozygous combinations of mutants for pygo and canonical Wnt signaling components had no additional effect on heart function over pygo heterozygotes alone. However, double knockdown of pygo and Ca2+/calmodulin-dependent protein kinase II caused additional arrhythmia compared with pygo knockdown alone, suggesting that some of the effects of pygo are mediated by Ca2+ signaling. In the isoproterenol-induced hypertrophic mouse model, we show that Pygo1 protein levels are increased. Conclusions Our data indicate that Pygo plays a critical role in adult heart function that is Wnt signaling independent and is likely conserved in mammals. PMID:24046329

  8. Curcumin Rescues Diabetic Renal Fibrosis by Targeting Superoxide-Mediated Wnt Signaling Pathways.

    Science.gov (United States)

    Ho, Cheng; Hsu, Yung-Chien; Lei, Chen-Chou; Mau, Shu-Ching; Shih, Ya-Hsueh; Lin, Chun-Liang

    2016-03-01

    The purposes of this study were to investigate whether curcumin can weaken diabetic nephropathy by modulating both oxidative stress and renal injury from Wnt signaling mediation. Wnt5a/β-catenin depression and induction of superoxide synthesis are associated with high glucose (HG) induced transforming growth factor (TGF)-β1 and fibronectin expression in mesangial cells. Curcumin resumes HG depression of Wnt/β-catenin signaling and alleviates HG induction of superoxide, TGF-β1 and fibronectin expression in renal mesangial cell. Exogenous curcumin alleviated urinary total proteinuria and serum superoxide level in diabetic rats. Based on laser-captured microdissection for quantitative real-time polymerase chain reaction, it was found that diabetes significantly increased TGF-β1 and fibronectin expression in line with depressed Wnt5a expression. Curcumin treatment reduced the TGF-β1 and fibronectin activation and the inhibiting effect of diabetes on Wnt5a/β-catenin expression in renal glomeruli. Immunohistochemistry showed that curcumin treatment significantly reduced 8-hydroxy-2'-deoxyguanosine, TGF-β1 and fibronectin, and was in line with the restoration of the suppressed Wnt5a expression immunoreactivities in glomeruli of diabetic rats. Curcumin alleviated extracellular matrix accumulation in diabetic nephropathy by not only preventing the diabetes-mediated superoxide synthesis but also resuming downregulation of Wnt/β-catenin signaling. These findings suggest that regulation of Wnt activity by curcumin is a feasible alternative strategy to rescue diabetic renal injury. Copyright © 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.

  9. The Role of Wnt Signaling in the Development of Alzheimer’s Disease: A Potential Therapeutic Target?

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    Wenbin Wan

    2014-01-01

    Full Text Available Accumulating evidence supports a key role for Wnt signaling in the development of the central nervous system (CNS during embryonic development and in the regulation of the structure and function of the adult brain. Alzheimer’s disease (AD is the most common form of senile dementia, which is characterized by β-amyloid (Aβ deposition in specific brain regions. However, the molecular mechanism underlying AD pathology remains elusive. Dysfunctional Wnt signaling is associated with several diseases such as epilepsy, cancer, metabolic disease, and AD. Increasing evidence suggests that downregulation of Wnt signaling, induced by Aβ, is associated with disease progression of AD. More importantly, persistent activation of Wnt signaling through Wnt ligands, or inhibition of negative regulators of Wnt signaling, such as Dickkopf-1 (DKK-1 and glycogen synthase kinase-3β (GSK-3β that are hyperactive in the disease state, is able to protect against Aβ toxicity and ameliorate cognitive performance in AD. Together, these data suggest that Wnt signaling might be a potential therapeutic target of AD. Here, we review recent studies related to the progression of AD where Wnt signaling might be relevant and participate in the development of the disease. Then, we focus on the potential relevance of manipulating the Wnt signaling pathway for the treatment of AD.

  10. Effect of activation of canonical Wnt signaling by the Wnt-3a protein on the susceptibility of PC12 cells to oxidative and apoptotic insults

    Directory of Open Access Journals (Sweden)

    E.M. Kawamoto

    2012-01-01

    Full Text Available Wnt proteins are involved in tissue development and their signaling pathways play an important role during embryogenesis. Wnt signaling can promote cell survival, which is beneficial for neurons, but could also lead to tumor development in different tissues. The present study investigated the effects of a Wnt protein on the susceptibility of a neural tumor cell line (PC12 cells to the cytotoxic compounds ferrous sulfate (10 mM, staurosporine (100 and 500 nM, 3-nitropropionic acid (5 mM, and amyloid β-peptide (Aβ25-35; 50 µM. Cells (1 x 10(6 cells/mL were treated with the Wnt-3a recombinant peptide (200 ng/mL for 24 h before exposure to toxic insults. The Wnt-3a protein partially protected PC12 cells, with a 6-15% increase in cell viability in the presence of toxic agents, similar to the effect measured using the MTT and lactate dehydrogenase cell viability assays. The Wnt-3a protein increased protein expression of β-catenin by 52% compared to control. These findings suggest that Wnt signaling can protect neural cells against apoptosis induced by toxic agents, which are relevant to the pathogenesis of Alzheimer’s and Huntington’s diseases.

  11. Effect of activation of canonical Wnt signaling by the Wnt-3a protein on the susceptibility of PC12 cells to oxidative and apoptotic insults

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    Kawamoto, E.M. [Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP (Brazil); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD (United States); Gleichmann, M. [Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD (United States); Yshii, L.M.; Sá Lima, L. de [Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP (Brazil); Mattson, M.P. [Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD (United States); Scavone, C. [Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP (Brazil)

    2011-11-25

    Wnt proteins are involved in tissue development and their signaling pathways play an important role during embryogenesis. Wnt signaling can promote cell survival, which is beneficial for neurons, but could also lead to tumor development in different tissues. The present study investigated the effects of a Wnt protein on the susceptibility of a neural tumor cell line (PC12 cells) to the cytotoxic compounds ferrous sulfate (10 mM), staurosporine (100 and 500 nM), 3-nitropropionic acid (5 mM), and amyloid β-peptide (Aβ{sub 25-35}; 50 µM). Cells (1 × 10{sup 6} cells/mL) were treated with the Wnt-3a recombinant peptide (200 ng/mL) for 24 h before exposure to toxic insults. The Wnt-3a protein partially protected PC12 cells, with a 6-15% increase in cell viability in the presence of toxic agents, similar to the effect measured using the MTT and lactate dehydrogenase cell viability assays. The Wnt-3a protein increased protein expression of β-catenin by 52% compared to control. These findings suggest that Wnt signaling can protect neural cells against apoptosis induced by toxic agents, which are relevant to the pathogenesis of Alzheimer's and Huntington's diseases.

  12. How the Wnt signaling pathway protects from neurodegeneration: The Mitochondrial Scenario

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    Macarena S. Arrázola

    2015-05-01

    Full Text Available Alzheimer´s disease (AD is the most common neurodegenerative disorder and is characterized by progressive memory loss and cognitive decline. One of the hallmarks of AD is the overproduction of amyloid-beta aggregates that range from the toxic soluble oligomer (Aβo form to extracellular accumulations in the brain. Growing evidence indicates that mitochondrial dysfunction is a common feature of neurodegenerative diseases and is observed at an early stage in the pathogenesis of AD. Reports indicate that mitochondrial structure and function are affected by Aβo and can trigger neuronal cell death. Mitochondria are highly dynamic organelles, and the balance between their fusion and fission processes is essential for neuronal function. Interestingly, in AD, the process known as mitochondrial dynamics is also impaired by Aβo. On the other hand, the activation of the Wnt signaling pathway has an essential role in synaptic maintenance and neuronal functions, and its deregulation has also been implicated in AD. We have demonstrated that canonical Wnt signaling, through the Wnt3a ligand, prevents the permeabilization of mitochondrial membranes through the inhibition of the mitochondrial permeability transition pore (mPTP, induced by Aβo. In addition, we showed that non-canonical Wnt signaling, through the Wnt5a ligand, protects mitochondria from fission-fusion alterations in AD. These results suggest new approaches by which different Wnt signaling pathways protect neurons in AD, and support the idea that mitochondria have become potential therapeutic targets for the treatment of neurodegenerative disorders. Here we discuss the neuroprotective role of the canonical and non-canonical Wnt signaling pathways in AD and their differential modulation of mitochondrial processes, associated with mitochondrial dysfunction and neurodegeneration.

  13. Mammary cells with active Wnt signaling resist ErbB2-induced tumorigenesis.

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    Wen Bu

    Full Text Available Aberrant activation of Wnt signaling is frequent in human malignancies. In normal epithelial tissues, including the breast, Wnt signaling is active only in a subset of cells, but it is unknown whether this subset of Wnt signaling-active cells is at increased risk of carcinogenesis. We created transgenic mice (TOP-tva in which the synthetic Wnt-responsive promoter TOP controlled the gene encoding TVA, which confers susceptibility to infection by the retroviral vector RCAS. Thus, only cells in which Wnt signaling is active will express tva and be targeted by RCAS. Surprisingly, we found that RCAS-mediated delivery of cDNA encoding a constitutively activated version of ErbB2 (HER2/Neu into the small number of TVA+ mammary epithelial cells in TOP-tva mice failed to induce tumor, while the same virus readily induced mammary tumors after it was delivered into a comparable number of cells in our previously reported mouse line MMTV-tva, whose tva is broadly expressed in mammary epithelium. Furthermore, we could not even detect any early lesions or infected cells in TOP-tva mice at the time of necropsy. Therefore, we conclude that the Wnt pathway-active cell subset in the normal mammary epithelium does not evolve into tumors following ErbB2 activation-rather, they apparently die due to apoptosis, an anticancer "barrier" that we have reported to be erected in some mammary cells followed ErbB2 activation. In accord with these mouse model data, we found that unlike the basal subtype, ErbB2+ human breast cancers rarely involve aberrant activation of Wnt signaling. This is the first report of a defined sub-population of mammalian cells that is "protected" from tumorigenesis by a potent oncogene, and provides direct in vivo evidence that mammary epithelial cells are not equal in their response to oncogene-initiated transformation.

  14. The pan-PI3K inhibitor GDC-0941 activates canonical WNT signaling to confer resistance in TNBC cells: resistance reversal with WNT inhibitor.

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    Tzeng, Huey-En; Yang, Lixin; Chen, Kemin; Wang, Yafan; Liu, Yun-Ru; Pan, Shiow-Lin; Gaur, Shikha; Hu, Shuya; Yen, Yun

    2015-05-10

    The pan-PI3K inhibitors are one treatment option for triple-negative breast cancer (TNBC). However, this treatment is ineffective for unknown reasons. Here, we report that aberrant expression of wingless-type MMTV integration site family (WNT) and activated WNT signals, which crosstalk with the PI3K-AKT-mTOR signaling pathway through GSK3β, plays the most critical role in resistance to pan-PI3K inhibitors in TNBC cells. GDC-0941 is a pan-PI3K inhibitor that activates the WNT/beta-catenin pathway in TNBC cells through stimulation of WNT secretion. GDC-0941-triggered WNT/beta-catenin pathway activation was observed in MDA-MB-231 and HCC1937 cells, which are TNBC cell lines showing aberrant WNT/beta-catenin activation, and not in SKBR3 and MCF7 cells. This observation is further investigated in vivo. GDC-0941 exhibited minimal tumor inhibition in MDA-MB-231 cells, but it significantly suppressed tumor growth in HER-positive SK-BR3 cells. In vivo mechanism study revealed the activation of WNT/beta-catenin pathway by GDC-0941. A synergistic effect was observed when combined treatment with GDC-0941 and the WNT inhibitor LGK974 at low concentrations in MDA-MB-231 cells. These findings indicated that WNT pathway activation conferred resistance in TNBC cells treated with GDC-0941. This resistance may be further circumvented through combined treatment with pan-PI3K and WNT inhibitors. Future clinical trials of these two inhibitors are warranted.

  15. Protein Phosphatase 2A in the Regulation of Wnt Signaling, Stem Cells, and Cancer

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    Joshua J. Thompson

    2018-02-01

    Full Text Available Protein phosphorylation is a ubiquitous cellular process that allows for the nuanced and reversible regulation of protein activity. Protein phosphatase 2A (PP2A is a heterotrimeric serine-threonine phosphatase—composed of a structural, regulatory, and catalytic subunit—that controls a variety of cellular events via protein dephosphorylation. While much is known about PP2A and its basic biochemistry, the diversity of its components—especially the multitude of regulatory subunits—has impeded the determination of PP2A function. As a consequence of this complexity, PP2A has been shown to both positively and negatively regulate signaling networks such as the Wnt pathway. Wnt signaling modulates major developmental processes, and is a dominant mediator of stem cell self-renewal, cell fate, and cancer stem cells. Because PP2A affects Wnt signaling both positively and negatively and at multiple levels, further understanding of this complex dynamic may ultimately provide insight into stem cell biology and how to better treat cancers that result from alterations in Wnt signaling. This review will summarize literature that implicates PP2A as a tumor suppressor, explore PP2A mutations identified in human malignancy, and focus on PP2A in the regulation of Wnt signaling and stem cells so as to better understand how aberrancy in this pathway can contribute to tumorigenesis.

  16. Merlin inhibits Wnt/β-catenin signaling by blocking LRP6 phosphorylation.

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    Kim, M; Kim, S; Lee, S-H; Kim, W; Sohn, M-J; Kim, H-S; Kim, J; Jho, E-H

    2016-10-01

    Merlin, encoded by the NF2 gene, is a tumor suppressor that acts by inhibiting mitogenic signaling and is mutated in Neurofibromatosis type II (NF2) disease, although its molecular mechanism is not fully understood. Here, we observed that Merlin inhibited Wnt/β-catenin signaling by blocking phosphorylation of LRP6, which is necessary for Wnt signal transduction, whereas mutated Merlin in NF2 patients did not. Treatment with Wnt3a enhanced phosphorylation of Ser518 in Merlin via activation of PAK1 in a PIP2-dependent manner. Phosphorylated Merlin dissociated from LRP6, allowing for phosphorylation of LRP6. Tissues from NF2 patients exhibited higher levels of β-catenin, and proliferation of RT4-D6P2T rat schwannoma cells was significantly reduced by treatment with chemical inhibitors of Wnt/β-catenin signaling. Taken together, our findings suggest that sustained activation of Wnt/β-catenin signaling due to abrogation of Merlin-mediated inhibition of LRP6 phosphorylation may be a cause of NF2 disease.

  17. Transposon Dysregulation Modulates dWnt4 Signaling to Control Germline Stem Cell Differentiation in Drosophila.

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    Maitreyi Upadhyay

    2016-03-01

    Full Text Available Germline stem cell (GSC self-renewal and differentiation are required for the sustained production of gametes. GSC differentiation in Drosophila oogenesis requires expression of the histone methyltransferase dSETDB1 by the somatic niche, however its function in this process is unknown. Here, we show that dSETDB1 is required for the expression of a Wnt ligand, Drosophila Wingless type mouse mammary virus integration site number 4 (dWnt4 in the somatic niche. dWnt4 signaling acts on the somatic niche cells to facilitate their encapsulation of the GSC daughter, which serves as a differentiation cue. dSETDB1 is known to repress transposable elements (TEs to maintain genome integrity. Unexpectedly, we found that independent upregulation of TEs also downregulated dWnt4, leading to GSC differentiation defects. This suggests that dWnt4 expression is sensitive to the presence of TEs. Together our results reveal a chromatin-transposon-Wnt signaling axis that regulates stem cell fate.

  18. Wnt/β-catenin-signaling and the formation of Müller glia-derived progenitors in the chick retina.

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    Gallina, Donika; Palazzo, Isabella; Steffenson, Lillia; Todd, Levi; Fischer, Andy J

    2016-09-01

    Müller glia can be stimulated to de-differentiate, proliferate, and form Müller glia-derived progenitor cells (MGPCs) that are capable of producing retinal neurons. The signaling pathways that influence the de-differentiation of mature Müller glia and proliferation of MGPCs may include the Wnt-pathway. The purpose of this study was to investigate how Wnt-signaling influences the formation of MGPCs in the chick retina in vivo. In NMDA-damaged retinas where MGPCs are known to form, we find dynamic changes in retinal levels of potential readouts of Wnt-signaling, including dkk1, dkk3, axin2, c-myc, tcf-1, and cd44. We find accumulations of nuclear β-catenin in MGPCs that peaks at 3 days and rapidly declines by 5 days after NMDA-treatment. Inhibition of Wnt-signaling with XAV939 in damaged retinas suppressed the formation of MGPCs, increased expression of ascl1a and decreased hes5, but had no effect upon the differentiation of progeny produced by MGPCs. Activation of Wnt-signaling, with GSK3β-inhibitors, in the absence of retinal damage, failed to stimulate the formation of MGPCs, whereas activation of Wnt-signaling in damaged retinas stimulated the formation of MGPCs. In the absence of retinal damage, FGF2/MAPK-signaling stimulated the formation of MGPCs by activating a signaling network that includes Wnt/β-catenin. In FGF2-treated retinas, inhibition of Wnt-signaling reduced numbers of proliferating MGPCs, whereas activation of Wnt-signaling failed to influence the formation of proliferating MGPCs. Our findings indicate that Wnt-signaling is part of a network initiated by FGF2/MAPK or retinal damage, and activation of canonical Wnt-signaling is required for the formation of proliferating MGPCs. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 983-1002, 2016. © 2015 Wiley Periodicals, Inc.

  19. R-spondin 3 regulates dorsoventral and anteroposterior patterning by antagonizing Wnt/β-catenin signaling in zebrafish embryos.

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    Xiaozhi Rong

    Full Text Available The Wnt/β-catenin or canonical Wnt signaling pathway plays fundamental roles in early development and in maintaining adult tissue homeostasis. R-spondin 3 (Rspo3 is a secreted protein that has been implicated in activating the Wnt/β-catenin signaling in amphibians and mammals. Here we report that zebrafish Rspo3 plays a negative role in regulating the zygotic Wnt/β-catenin signaling. Zebrafish Rspo3 has a unique domain structure. It contains a third furin-like (FU3 domain. This FU3 is present in other four ray-finned fish species studied but not in elephant shark. In zebrafish, rspo3 mRNA is maternally deposited and has a ubiquitous expression in early embryonic stages. After 12 hpf, its expression becomes tissue-specific. Forced expression of rspo3 promotes dorsoanterior patterning and increases the expression of dorsal and anterior marker genes. Knockdown of rspo3 increases ventral-posterior development and stimulates ventral and posterior marker genes expression. Forced expression of rspo3 abolishes exogenous Wnt3a action and reduces the endogenous Wnt signaling activity. Knockdown of rspo3 results in increased Wnt/β-catenin signaling activity. Further analyses indicate that Rspo3 does not promote maternal Wnt signaling. Human RSPO3 has similar action when tested in zebrafish embryos. These results suggest that Rspo3 regulates dorsoventral and anteroposterior patterning by negatively regulating the zygotic Wnt/β-catenin signaling in zebrafish embryos.

  20. A proteomic analysis of LRRK2 binding partners reveals interactions with multiple signaling components of the WNT/PCP pathway.

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    Salašová, Alena; Yokota, Chika; Potěšil, David; Zdráhal, Zbyněk; Bryja, Vítězslav; Arenas, Ernest

    2017-07-11

    Autosomal-dominant mutations in the Park8 gene encoding Leucine-rich repeat kinase 2 (LRRK2) have been identified to cause up to 40% of the genetic forms of Parkinson's disease. However, the function and molecular pathways regulated by LRRK2 are largely unknown. It has been shown that LRRK2 serves as a scaffold during activation of WNT/β-catenin signaling via its interaction with the β-catenin destruction complex, DVL1-3 and LRP6. In this study, we examine whether LRRK2 also interacts with signaling components of the WNT/Planar Cell Polarity (WNT/PCP) pathway, which controls the maturation of substantia nigra dopaminergic neurons, the main cell type lost in Parkinson's disease patients. Co-immunoprecipitation and tandem mass spectrometry was performed in a mouse substantia nigra cell line (SN4741) and human HEK293T cell line in order to identify novel LRRK2 binding partners. Inhibition of the WNT/β-catenin reporter, TOPFlash, was used as a read-out of WNT/PCP pathway activation. The capacity of LRRK2 to regulate WNT/PCP signaling in vivo was tested in Xenopus laevis' early development. Our proteomic analysis identified that LRRK2 interacts with proteins involved in WNT/PCP signaling such as the PDZ domain-containing protein GIPC1 and Integrin-linked kinase (ILK) in dopaminergic cells in vitro and in the mouse ventral midbrain in vivo. Moreover, co-immunoprecipitation analysis revealed that LRRK2 binds to two core components of the WNT/PCP signaling pathway, PRICKLE1 and CELSR1, as well as to FLOTILLIN-2 and CULLIN-3, which regulate WNT secretion and inhibit WNT/β-catenin signaling, respectively. We also found that PRICKLE1 and LRRK2 localize in signalosomes and act as dual regulators of WNT/PCP and β-catenin signaling. Accordingly, analysis of the function of LRRK2 in vivo, in X. laevis revelaed that LRKK2 not only inhibits WNT/β-catenin pathway, but induces a classical WNT/PCP phenotype in vivo. Our study shows for the first time that LRRK2 activates the WNT

  1. Wnt signaling in ovarian development inhibits Sf1 activation of Sox9 via the Tesco enhancer.

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    Bernard, Pascal; Ryan, Janelle; Sim, Helena; Czech, Daniel P; Sinclair, Andrew H; Koopman, Peter; Harley, Vincent R

    2012-02-01

    Genome analysis of patients with disorders of sex development, and gain- and loss-of-function studies in mice indicate that gonadal development is regulated by opposing signals. In females, the Wnt/β-catenin canonical pathway blocks testicular differentiation by repressing the expression of the Sertoli cell-specific gene Sox9 by an unknown mechanism. Using cell and embryonic gonad culture models, we show that activation of the Wnt/β-catenin pathway inhibits the expression of Sox9 and Amh, whereas mRNA and protein levels of Sry and steroidogenic factor 1 (Sf1), two key transcriptional regulators of Sox9, are not altered. Ectopic activation of Wnt/β-catenin signaling in male gonads led to a loss of Sf1 binding to the Tesco enhancer and absent Sox9 expression that we also observed in wild-type ovaries. Moreover, ectopic Wnt/β-catenin signaling induced the expression of the female somatic cell markers, Bmp2 and Rspo1, as a likely consequence of Sox9 loss. Wnt/β-catenin signaling in XY gonads did not, however, affect gene expression of the steroidogenic Leydig cell Sf1 target gene, Cyp11a1, or Sf1 binding to the Cyp11a1 promoter. Our data support a model in ovary development whereby activation of β-catenin prevents Sf1 binding to the Sox9 enhancer, thereby inhibiting Sox9 expression and Sertoli cell differentiation.

  2. Radial glial neural progenitors regulate nascent brain vascular network stabilization via inhibition of Wnt signaling.

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    Shang Ma

    Full Text Available The cerebral cortex performs complex cognitive functions at the expense of tremendous energy consumption. Blood vessels in the brain are known to form stereotypic patterns that facilitate efficient oxygen and nutrient delivery. Yet little is known about how vessel development in the brain is normally regulated. Radial glial neural progenitors are well known for their central role in orchestrating brain neurogenesis. Here we show that, in the late embryonic cortex, radial glial neural progenitors also play a key role in brain angiogenesis, by interacting with nascent blood vessels and regulating vessel stabilization via modulation of canonical Wnt signaling. We find that ablation of radial glia results in vessel regression, concomitant with ectopic activation of Wnt signaling in endothelial cells. Direct activation of Wnt signaling also results in similar vessel regression, while attenuation of Wnt signaling substantially suppresses regression. Radial glial ablation and ectopic Wnt pathway activation leads to elevated endothelial expression of matrix metalloproteinases, while inhibition of metalloproteinase activity significantly suppresses vessel regression. These results thus reveal a previously unrecognized role of radial glial progenitors in stabilizing nascent brain vascular network and provide novel insights into the molecular cascades through which target neural tissues regulate vessel stabilization and patterning during development and throughout life.

  3. BAMBI Promotes C2C12 Myogenic Differentiation by Enhancing Wnt/β-Catenin Signaling

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    Qiangling Zhang

    2015-08-01

    Full Text Available Bone morphogenic protein and activin membrane-bound inhibitor (BAMBI is regarded as an essential regulator of cell proliferation and differentiation that represses transforming growth factor-β and enhances Wnt/β-catenin signaling in various cell types. However, its role in skeletal muscle remains largely unknown. In the current study, we found that the expression level of BAMBI peaked in the early differentiation phase of the C2C12 rodent myoblast cell line. Knockdown of BAMBI via siRNA inhibited C2C12 differentiation, indicated by repressed MyoD, MyoG, and MyHC expression as well as reductions in the differentiation and fusion indices. BAMBI knockdown reduced the activity of Wnt/β-catenin signaling, as characterized by the decreased nuclear translocation of β-catenin and the lowered transcription of Axin2, which is a well-documented target gene of the Wnt/β-catenin signaling pathway. Furthermore, treatment with LiCl, an activator of Wnt/β-catenin signaling, rescued the reduction in C2C12 differentiation caused by BAMBI siRNA. Taken together, our data suggest that BAMBI is required for normal C2C12 differentiation, and that its role in myogenesis is mediated by the Wnt/β-catenin pathway.

  4. The role of the Wnt signaling pathway in cancer stem cells: prospects for drug development

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    Kim YM

    2014-07-01

    Full Text Available Yong-Mi Kim,1 Michael Kahn2,3 1Children's Hospital Los Angeles, Division of Hematology and Oncology, Department of Pediatrics and Pathology, 2Department of Biochemistry and Molecular Biology, Keck School of Medicine of University of Southern California, 3Norris Comprehensive Cancer Research Center, University of Southern California, Los Angeles, CA, USA Abstract: Cancer stem cells (CSCs, also known as tumor initiating cells are now considered to be the root cause of most if not all cancers, evading treatment and giving rise to disease relapse. They have become a central focus in new drug development. Prospective identification, understanding the key pathways that maintain CSCs, and being able to target CSCs, particularly if the normal stem cell population could be spared, could offer an incredible therapeutic advantage. The Wnt signaling cascade is critically important in stem cell biology, both in homeostatic maintenance of tissues and organs through their respective somatic stem cells and in the CSC/tumor initiating cell population. Aberrant Wnt signaling is associated with a wide array of tumor types. Therefore, the ability to safely target the Wnt signaling pathway offers enormous promise to target CSCs. However, just like the sword of Damocles, significant risks and concerns regarding targeting such a critical pathway in normal stem cell maintenance and tissue homeostasis remain ever present. With this in mind, we review recent efforts in modulating the Wnt signaling cascade and critically analyze therapeutic approaches at various stages of development. Keywords: beta-catenin, CBP, p300, wnt inhibition

  5. Vitamin D Is a Multilevel Repressor of Wnt/β-Catenin Signaling in Cancer Cells

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    Larriba, María Jesús; González-Sancho, José Manuel; Barbáchano, Antonio; Niell, Núria; Ferrer-Mayorga, Gemma; Muñoz, Alberto, E-mail: amunoz@iib.uam.es [Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Arturo Duperier 4, Madrid 28029 (Spain)

    2013-10-21

    The Wnt/β-catenin signaling pathway is abnormally activated in most colorectal cancers and in a proportion of other neoplasias. This activation initiates or contributes to carcinogenesis by regulating the expression of a large number of genes in tumor cells. The active vitamin D metabolite 1α,25-dihydroxyvitamin D{sub 3} (1,25(OH){sub 2}D{sub 3}) inhibits Wnt/β-catenin signaling by several mechanisms at different points along the pathway. Additionally, paracrine actions of 1,25(OH){sub 2}D{sub 3} on stromal cells may also repress this pathway in neighbouring tumor cells. Here we review the molecular basis for the various mechanisms by which 1,25(OH){sub 2}D{sub 3} antagonizes Wnt/β-catenin signaling, preferentially in human colon carcinoma cells, and the consequences of this inhibition for the phenotype and proliferation rate. The effect of the vitamin D system on Wnt/β-catenin signaling and tumor growth in animal models will also be commented in detail. Finally, we revise existing data on the relation between vitamin D receptor expression and vitamin D status and the expression of Wnt/β-catenin pathway genes and targets in cancer patients.

  6. Twist1 contributes to cranial bone initiation and dermal condensation by maintaining Wnt signaling responsiveness

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    Goodnough, L. Henry; DiNuoscio, Gregg J.; Atit, Radhika P.

    2015-01-01

    Background Specification of cranial bone and dermal fibroblast progenitors in the supraorbital arch mesenchyme is Wnt/β-catenin signaling-dependent. The mechanism underlying how these cells interpret instructive signaling cues and differentiate into these two lineages is unclear. Twist1 is a target of the Wnt/β-catenin signaling pathway and is expressed in cranial bone and dermal lineages. Results Here, we show that onset of Twist1 expression in the mouse cranial mesenchyme is dependent on ectodermal Wnts and mesenchymal β-catenin activity. Conditional deletion of Twist1 in the supraorbital arch mesenchyme leads to cranial bone agenesis and hypoplastic dermis, as well as craniofacial malformation of eyes and palate. Twist1 is preferentially required for cranial bone lineage commitment by maintaining Wnt responsiveness. In the conditional absence of Twist1, the cranial dermis fails to condense and expand apically leading to extensive cranial dermal hypoplasia with few and undifferentiated hair follicles. Conclusions Thus, Twist1, a target of canonical Wnt/β-catenin signaling, also functions to maintain Wnt responsiveness and is a key effector for cranial bone fate selection and dermal condensation. PMID:26677825

  7. Modeling oscillatory control in NF-¿B, p53 and Wnt signaling

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    Mengel, Benedicte; Hunziker, Alexander; Pedersen, Lykke

    2010-01-01

    Oscillations are commonly observed in cellular behavior and span a wide range of timescales, from seconds in calcium signaling to 24 hours in circadian rhythms. In between lie oscillations with time periods of 1-5 hours seen in NF-¿B, p53 and Wnt signaling, which play key roles in the immune system...

  8. WNT signalling events near the cell membrane and their pharmacological targeting for the treatment of cancer

    NARCIS (Netherlands)

    Driehuis, Else; Clevers, Hans

    2017-01-01

    WNT signalling is an essential signalling pathway for all multicellular animals. Although first described more than 30 years ago, new components and regulators of the pathway are still being discovered. Considering its importance in both embryonic development and adult homeostasis, it is not

  9. The role of Ryk and Ror receptor tyrosine kinases in Wnt signal transduction.

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    Green, Jennifer; Nusse, Roel; van Amerongen, Renée

    2014-02-01

    Receptor tyrosine kinases of the Ryk and Ror families were initially classified as orphan receptors because their ligands were unknown. They are now known to contain functional extracellular Wnt-binding domains and are implicated in Wnt-signal transduction in multiple species. Although their signaling mechanisms still remain to be resolved in detail, both Ryk and Ror control important developmental processes in different tissues. However, whereas many other Wnt-signaling responses affect cell proliferation and differentiation, Ryk and Ror are mostly associated with controlling processes that rely on the polarized migration of cells. Here we discuss what is currently known about the involvement of this exciting class of receptors in development and disease.

  10. Flavonoids and Wnt/β-Catenin Signaling: Potential Role in Colorectal Cancer Therapies

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    Nathália G. Amado

    2014-07-01

    Full Text Available It is now well documented that natural products have played an important role in anticancer therapy. Many studies focus on the ability of these natural compounds to modulate tumor-related signaling pathways and the relationship of these properties to an anticancer effect. According to the World Health Organization (WHO, colorectal cancer (CRC is the third most common cancer and the fourth leading cause of cancer death among men and women. Therefore, finding strategies to fight against CRC is an emergent health problem. CRC has a strong association with deregulation of Wnt/β-catenin signaling pathway. As some types of natural compounds are capable of modulating the Wnt/β-catenin signaling, one important question is whether they could counteract CRC. In this review, we discuss the role of flavonoids, a class of natural compounds, on Wnt/β-catenin regulation and its possible potential for therapeutic usage on colorectal cancer.

  11. AP1- and NF-kappaB-binding sites conserved among mammalian WNT10B orthologs elucidate the TNFalpha-WNT10B signaling loop implicated in carcinogenesis and adipogenesis.

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    Katoh, Masuko; Katoh, Masaru

    2007-04-01

    WNT signals are context-dependently transduced to canonical and non-canonical signaling cascades. We cloned and characterized wild-type human WNT10B, while another group cloned aberrant human WNT10B with Gly60Asp amino-acid substitution. Proto-oncogene WNT10B is expressed in gastric cancer, pancreatic cancer, breast cancer, esophageal cancer, and cervical cancer. Because WNT10B blocks adipocyte differentiation, coding SNP of WNT10B gene is associated with familial obesity. In 2001, we reported WNT10B upregulation by TNFalpha. Here, comparative integromics analyses on WNT10B orthologs were performed to elucidate the transcriptional mechanism of WNT10B. Chimpanzee WNT10B and cow Wnt10b genes were identified within NW_001223159.1 and AC150975.2 genome sequences, respectively, by using bioinformatics (Techint) and human intelligence (Humint). Chimpanzee WNT10B and cow Wnt10b showed 98.7% and 95.1% total-amino-acid identity with human WNT10B, respectively. N-terminal signal peptide, 24 Cys residues, two Asn-linked glycosylation sites, and Gly60 of human WNT10B were conserved among mammalian WNT10B orthologs. Transcription start site of human WNT10B gene was 106-bp upstream of NM_003394.2 RefSeq 5'-end. Number of GC di-nucleotide repeats just down-stream of WNT10B transcription start site varied among primates and human population. Comparative genomics analyses revealed that double AP1-binding sites in the 5'-flanking promoter region and NF-kappaB-binding site in intron 3 were conserved among human, chimpanzee, cow, mouse, and rat WNT10B orthologs. Because TNFalpha signaling through TNFR1 and TRADD/RIP/TRAF2 complex activates JUN kinase (JNK) and IkappaB kinase (IKK) signaling cascades, conserved AP1- and NF-kappaB-binding sites explain the mechanism of TNFalpha-induced WNT10B upregulation. TNFalpha-WNT10B signaling loop is the negative feedback mechanism of adipogenesis to prevent obesity and metabolic syndrome. On the other hand, TNFalpha-WNT10B signaling loop is

  12. Rac1 modulates mammalian lung branching morphogenesis in part through canonical Wnt signaling.

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    Danopoulos, Soula; Krainock, Michael; Toubat, Omar; Thornton, Matthew; Grubbs, Brendan; Al Alam, Denise

    2016-12-01

    Lung branching morphogenesis relies on a number of factors, including proper epithelial cell proliferation and differentiation, cell polarity, and migration. Rac1, a small Rho GTPase, orchestrates a number of these cellular processes, including cell proliferation and differentiation, cellular alignment, and polarization. Furthermore, Rac1 modulates both noncanonical and canonical Wnt signaling, important pathways in lung branching morphogenesis. Culture of embryonic mouse lung explants in the presence of the Rac1 inhibitor (NSC23766) resulted in a dose-dependent decrease in branching. Increased cell death and BrdU uptake were notably seen in the mesenchyme, while no direct effect on the epithelium was observed. Moreover, vasculogenesis was impaired following Rac1 inhibition as shown by decreased Vegfa expression and impaired LacZ staining in Flk1-Lacz reporter mice. Rac1 inhibition decreased Fgf10 expression in conjunction with many of its associated factors. Moreover, using the reporter lines TOPGAL and Axin2-LacZ, there was an evident decrease in canonical Wnt signaling in the explants treated with the Rac1 inhibitor. Activation of canonical Wnt pathway using WNT3a or WNT7b only partially rescued the branching inhibition. Moreover, these results were validated on human explants, where Rac1 inhibition resulted in impaired branching and decreased AXIN2 and FGFR2b expression. We therefore conclude that Rac1 regulates lung branching morphogenesis, in part through canonical Wnt signaling. However, the exact mechanisms by which Rac1 interacts with canonical Wnt in human and mouse lung requires further investigation. Copyright © 2016 the American Physiological Society.

  13. FHL2 silencing reduces Wnt signaling and osteosarcoma tumorigenesis in vitro and in vivo.

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    Julia Brun

    Full Text Available BACKGROUND: The molecular mechanisms that are involved in the growth and invasiveness of osteosarcoma, an aggressive and invasive primary bone tumor, are not fully understood. The transcriptional co-factor FHL2 (four and a half LIM domains protein 2 acts as an oncoprotein or as a tumor suppressor depending on the tissue context. In this study, we investigated the role of FHL2 in tumorigenesis in osteosarcoma model. METHODOLOGY/PRINCIPAL FINDINGS: Western blot analyses showed that FHL2 is expressed above normal in most human and murine osteosarcoma cells. Tissue microarray analysis revealed that FHL2 protein expression is high in human osteosarcoma and correlates with osteosarcoma aggressiveness. In murine osteosarcoma cells, FHL2 silencing using shRNA decreased canonical Wnt/β-catenin signaling and reduced the expression of Wnt responsive genes as well as of the key Wnt molecules Wnt5a and Wnt10b. This effect resulted in inhibition of osteosarcoma cell proliferation, invasion and migration in vitro. Using xenograft experiments, we showed that FHL2 silencing markedly reduced tumor growth and lung metastasis occurence in mice. The anti-oncogenic effect of FHL2 silencing in vivo was associated with reduced cell proliferation and decreased Wnt signaling in the tumors. CONCLUSION/SIGNIFICANCE: Our findings demonstrate that FHL2 acts as an oncogene in osteosarcoma cells and contributes to tumorigenesis through Wnt signaling. More importantly, FHL2 depletion greatly reduces tumor cell growth and metastasis, which raises the potential therapeutic interest of targeting FHL2 to efficiently impact primary bone tumors.

  14. ERβ induces the differentiation of cultured osteoblasts by both Wnt/β-catenin signaling pathway and estrogen signaling pathways

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    Yin, Xinhua [Department of Spine Surgery, Xiangya Hospital of Central South University, Changsha (China); Wang, Xiaoyuan [Department of Nephrology, Xi An Honghui Hospital, Xi an (China); Hu, Xiongke; Chen, Yong; Zeng, Kefeng [Department of Spine Surgery, Xiangya Hospital of Central South University, Changsha (China); Zhang, Hongqi, E-mail: zhq9699@126.com [Department of Spine Surgery, Xiangya Hospital of Central South University, Changsha (China)

    2015-07-01

    Although 17β-estradial (E2) is known to stimulate bone formation, the underlying mechanisms are not fully understood. Recent studies have implicated the Wnt/β-catenin pathway as a major signaling cascade in bone biology. The interactions between Wnt/β-catenin signaling pathway and estrogen signaling pathways have been reported in many tissues. In this study, E2 significantly increased the expression of β-catenin by inducing phosphorylations of GSK3β at serine 9. ERβ siRNAs were transfected into MC3T3-E1 cells and revealed that ERβ involved E2-induced osteoblasts proliferation and differentiation via Wnt/β-catenin signaling. The osteoblast differentiation genes (BGP, ALP and OPN) and proliferation related gene (cyclin D1) expression were significantly induced by E2-mediated ERβ. Furthermore immunofluorescence and immunoprecipitation analysis demonstrated that E2 induced the accumulation of β-catenin protein in the nucleus which leads to interaction with T-cell-specific transcription factor/lymphoid enhancer binding factor (TCF/LEF) transcription factors. Taken together, these findings suggest that E2 promotes osteoblastic proliferation and differentiation by inducing proliferation-related and differentiation-related gene expression via ERβ/GSK-3β-dependent Wnt/β-catenin signaling pathway. Our findings provide novel insights into the mechanisms of action of E2 in osteoblastogenesis. - Highlights: • 17β-estradial (E2) promotes GSK3-β phosphorylation. • E2 activates the Wnt/β-catenin signaling pathway. • The Wnt/β-catenin signaling pathway interacts with estrogen signaling pathways. • E2-mediated ER induced osteoblast differentiation and proliferation related genes expression.

  15. A Wnt5a signaling pathway in the pathogenesis of HIV-1 gp120-induced pain.

    Science.gov (United States)

    Yuan, Su-Bo; Ji, Guangchen; Li, Bei; Andersson, Tommy; Neugebauer, Volker; Tang, Shao-Jun

    2015-07-01

    Pathological pain is one of the most common neurological complications in patients with HIV-1/AIDS. However, the pathogenic process is unclear. Our recent studies show that Wnt5a is upregulated in the spinal cord dorsal horn (SDH) of the patients with HIV who develop pain and that HIV-1 gp120, a potential causal factor of the HIV-associated pain, rapidly upregulates Wnt5a in the mouse SDH. Using a mouse model, we show here that a specific Wnt5a antagonist, Box-5, attenuated gp120-induced mechanical allodynia. Conversely, a Wnt5a agonist, Foxy5, facilitated the allodynia. To elucidate the molecular mechanism by which Wnt5a regulates gp120-induced allodynia, we tested the role of the JNK/TNF-α pathway. We observed that the JNK-specific inhibitor SP600125 blocked either gp120- or Foxy5-induced allodynia. Similarly, the TNF-α-specific antagonist Enbrel also reversed either gp120- or Foxy5-induced allodynia. These data suggest that JNK and TNF-α mediate the biological effects of Wnt5a in regulating gp120-induced allodynia. To investigate the cellular mechanism, we performed extracellular single-unit recording from SDH neurons in anesthetized mice. Both Box-5 and SP600125 negated gp120-induced potentiation of SDH neuron spiking evoked by mechanical stimulation of the hind paw. Furthermore, while Foxy5 potentiated spike frequency of SDH neurons, either SP600125 or Enbrel blocked the potentiation. The data indicate that Wnt5a potentiates the activity of SDH neurons through the JNK-TNF-α pathway. Collectively, our findings suggest that Wnt5a regulates the pathogenesis of gp120-induced pain, likely by sensitizing pain-processing SDH neurons through JNK/TNF-α signaling.

  16. Wnt/β-catenin signalling and podocyte dysfunction in proteinuric kidney disease

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    Zhou, Lili; Liu, Youhua

    2016-01-01

    Podocytes are unique, highly specialized, terminally differentiated cells that are integral components of the kidney glomerular filtration barrier. Podocytes are vulnerable to a variety of injuries and in response they undergo a series of changes ranging from hypertrophy, autophagy, dedifferentiation, mesenchymal transition and detachment to apoptosis, depending on the nature and extent of the insult. Emerging evidence indicates that Wnt/β-catenin signalling has a central role in mediating podocyte dysfunction and proteinuria. Wnts are induced and β-catenin is activated in podocytes in various proteinuric kidney diseases. Genetic or pharmacologic activation of β-catenin is sufficient to impair podocyte integrity and causes proteinuria in healthy mice, whereas podocyte-specific ablation of β-catenin protects against proteinuria after kidney injury. Mechanistically, Wnt/β-catenin controls the expression of several key mediators implicated in podocytopathies, including Snail1, the renin–angiotensin system and matrix metalloproteinase 7. Wnt/β-catenin also negatively regulates Wilms tumour protein, a crucial transcription factor that safeguards podocyte integrity. Targeted inhibition of Wnt/β-catenin signalling preserves podocyte integrity and ameliorates proteinuria in animal models. This Review highlights advances in our understanding of the pathomechanisms of Wnt/β-catenin signalling in mediating podocyte injury, and describes the therapeutic potential of targeting this pathway for the treatment of proteinuric kidney disease. PMID:26055352

  17. Plakophilin-1, a Novel Wnt Signaling Regulator, Is Critical for Tooth Development and Ameloblast Differentiation.

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    Miyazaki, Kanako; Yoshizaki, Keigo; Arai, Chieko; Yamada, Aya; Saito, Kan; Ishikawa, Masaki; Xue, Han; Funada, Keita; Haruyama, Naoto; Yamada, Yoshihiko; Fukumoto, Satoshi; Takahashi, Ichiro

    2016-01-01

    Tooth morphogenesis is initiated by reciprocal interactions between the ectoderm and neural crest-derived mesenchyme, and the Wnt signaling pathway is involved in this process. We found that Plakophilin (PKP)1, which is associated with diseases such as ectodermal dysplasia/skin fragility syndrome, was highly expressed in teeth and skin, and was upregulated during tooth development. We hypothesized that PKP1 regulates Wnt signaling via its armadillo repeat domain in a manner similar to β-catenin. To determine its role in tooth development, we performed Pkp1 knockdown experiments using ex vivo organ cultures and cell cultures. Loss of Pkp1 reduced the size of tooth germs and inhibited dental epithelial cell proliferation, which was stimulated by Wnt3a. Furthermore, transfected PKP1-emerald green fluorescent protein was translocated from the plasma membrane to the nucleus upon stimulation with Wnt3a and LiCl, which required the PKP1 N terminus (amino acids 161 to 270). Localization of PKP1, which is known as an adhesion-related desmosome component, shifted to the plasma membrane during ameloblast differentiation. In addition, Pkp1 knockdown disrupted the localization of Zona occludens 1 in tight junctions and inhibited ameloblast differentiation; the two proteins were shown to directly interact by immunoprecipitation. These results implicate the participation of PKP1 in early tooth morphogenesis as an effector of canonical Wnt signaling that controls ameloblast differentiation via regulation of the cell adhesion complex.

  18. Plakophilin-1, a Novel Wnt Signaling Regulator, Is Critical for Tooth Development and Ameloblast Differentiation.

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    Kanako Miyazaki

    Full Text Available Tooth morphogenesis is initiated by reciprocal interactions between the ectoderm and neural crest-derived mesenchyme, and the Wnt signaling pathway is involved in this process. We found that Plakophilin (PKP1, which is associated with diseases such as ectodermal dysplasia/skin fragility syndrome, was highly expressed in teeth and skin, and was upregulated during tooth development. We hypothesized that PKP1 regulates Wnt signaling via its armadillo repeat domain in a manner similar to β-catenin. To determine its role in tooth development, we performed Pkp1 knockdown experiments using ex vivo organ cultures and cell cultures. Loss of Pkp1 reduced the size of tooth germs and inhibited dental epithelial cell proliferation, which was stimulated by Wnt3a. Furthermore, transfected PKP1-emerald green fluorescent protein was translocated from the plasma membrane to the nucleus upon stimulation with Wnt3a and LiCl, which required the PKP1 N terminus (amino acids 161 to 270. Localization of PKP1, which is known as an adhesion-related desmosome component, shifted to the plasma membrane during ameloblast differentiation. In addition, Pkp1 knockdown disrupted the localization of Zona occludens 1 in tight junctions and inhibited ameloblast differentiation; the two proteins were shown to directly interact by immunoprecipitation. These results implicate the participation of PKP1 in early tooth morphogenesis as an effector of canonical Wnt signaling that controls ameloblast differentiation via regulation of the cell adhesion complex.

  19. Wnt isoform-specific interactions with coreceptor specify inhibition or potentiation of signaling by LRP6 antibodies.

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    Yan Gong

    Full Text Available β-Catenin-dependent Wnt signaling is initiated as Wnt binds to both the receptor FZD and coreceptor LRP5/6, which then assembles a multimeric complex at the cytoplasmic membrane face to recruit and inactivate the kinase GSK3. The large number and sequence diversity of Wnt isoforms suggest the possibility of domain-specific ligand-coreceptor interactions, and distinct binding sites on LRP6 for Wnt3a and Wnt9b have recently been identified in vitro. Whether mechanistically different interactions between Wnts and coreceptors might mediate signaling remains to be determined. It is also not clear whether coreceptor homodimerization induced extracellularly can activate Wnt signaling, as is the case for receptor tyrosine kinases. We generated monoclonal antibodies against LRP6 with the unexpected ability to inhibit signaling by some Wnt isoforms and potentiate signaling by other isoforms. In cell culture, two antibodies characterized further show reciprocal activities on most Wnts, with one antibody antagonizing and the other potentiating. We demonstrate that these antibodies bind to different regions of LRP6 protein, and inhibition of signaling results from blocking Wnt binding. Antibody-mediated dimerization of LRP6 can potentiate signaling only when a Wnt isoform is also able to bind the complex, presumably recruiting FZD. Endogenous autocrine Wnt signaling in different tumor cell lines can be either antagonized or enhanced by the LRP6 antibodies, indicating expression of different Wnt isoforms. As anticipated from the roles of Wnt signaling in cancer and bone development, antibody activities can also be observed in mice for inhibition of tumor growth and in organ culture for enhancement of bone mineral density. Collectively, our results indicate that separate binding sites for different subsets of Wnt isoforms determine the inhibition or potentiation of signaling conferred by LRP6 antibodies. This complexity of coreceptor-ligand interactions may

  20. T-cell factor 4 (tcf7l2) is the main effector of Wnt signaling during zebrafish intestine organogenesis.

    Science.gov (United States)

    Faro, Ana; Boj, Sylvia F; Ambrósio, Raquel; van den Broek, Olaf; Korving, Jeroen; Clevers, Hans

    2009-03-01

    The Wnt pathway orchestrates cell fate decisions during embryonic development, organogenesis, and adult tissues homeostasis. T-cell factor (Tcf )/lymphoid enhancer-binding factor (Lef) transcription factors are the downstream effectors of canonical Wnt signaling. Upon Wnt signal activation, beta-catenin stabilizes and translocates to the nucleus, where it interacts with Tcfs activating the transcription of Wnt target genes. In the absence of Wnt, levels of stable beta-catenin are reduced by the action of adenomatous polyposis coli (Apc) and other cytoplasmic proteins. Mutations in Apc cause constitutive accumulation of beta-catenin and inappropriate activation of the Wnt pathway. apc(mcr/mcr) fish embryos show absence of expression of tissue-specific differentiation markers in the intestine, suggesting that inappropriate activation of Wnt signaling abrogates gut organogenesis. Which Tcf transcription factor mediates Wnt signaling during zebrafish gut organogenesis remains unclear. We studied the combined effect of loss of Tcf family members and Apc in the developing embryo. Tcf4 (tcf7l2) loss rescues the apc(mcr/mcr) phenotype in the intestine. Single depletion of Tcf1 (tcf7) and Tcf3 (tcf7l1a) function in an Apc mutant background had no effect on endoderm development. This study reveals that Tcf4 (tcf7l2) is the major effector of Wnt signaling in the intestine during zebrafish organogenesis.

  1. CACN-1/Cactin plays a role in Wnt signaling in C. elegans.

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    Melissa LaBonty

    Full Text Available Wnt signaling is tightly regulated during animal development and controls cell proliferation and differentiation. In C. elegans, activation of Wnt signaling alters the activity of the TCF/LEF transcription factor, POP-1, through activation of the Wnt/β-catenin or Wnt/β-catenin asymmetry pathways. In this study, we have identified CACN-1 as a potential regulator of POP-1 in C. elegans larval development. CACN-1/Cactin is a well-conserved protein of unknown molecular function previously implicated in the regulation of several developmental signaling pathways. Here we have used activation of POPTOP, a POP-1-responsive reporter construct, as a proxy for Wnt signaling. POPTOP requires POP-1 and SYS-1/β-catenin for activation in L4 uterine cells. RNAi depletion experiments show that CACN-1 is needed to prevent excessive activation of POPTOP and for proper levels and/or localization of POP-1. Surprisingly, high POPTOP expression correlates with increased levels of POP-1 in uterine nuclei, suggesting POPTOP may not mirror endogenous gene expression in all respects. Genetic interaction studies suggest that CACN-1 may act partially through LIT-1/NLK to alter POP-1 localization and POPTOP activation. Additionally, CACN-1 is required for proper proliferation of larval seam cells. Depletion of CACN-1 results in a loss of POP-1 asymmetry and reduction of terminal seam cell number, suggesting an adoption of the anterior, differentiated fate by the posterior daughter cells. These findings suggest CACN-1/Cactin modulates Wnt signaling during larval development.

  2. Activation of Wnt signaling by chemically induced dimerization of LRP5 disrupts cellular homeostasis.

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    Payam Shahi

    Full Text Available Wnt signaling is crucial for a variety of biological processes, including body axis formation, planar polarity, stem cell maintenance and cellular differentiation. Therefore, targeted manipulation of Wnt signaling in vivo would be extremely useful. By applying chemical inducer of dimerization (CID technology, we were able to modify the Wnt co-receptor, low-density lipoprotein (LDL-receptor-related protein 5 (LRP5, to generate the synthetic ligand inducible Wnt switch, iLRP5. We show that iLRP5 oligomerization results in its localization to disheveled-containing punctate structures and sequestration of scaffold protein Axin, leading to robust β-catenin-mediated signaling. Moreover, we identify a novel LRP5 cytoplasmic domain critical for its intracellular localization and casein kinase 1-dependent β-catenin signaling. Finally, by utilizing iLRP5 as a Wnt signaling switch, we generated the Ubiquitous Activator of β-catenin (Ubi-Cat transgenic mouse line. The Ubi-Cat line allows for nearly ubiquitous expression of iLRP5 under control of the H-2K(b promoter. Activation of iLRP5 in isolated prostate basal epithelial stem cells resulted in expansion of p63(+ cells and development of hyperplasia in reconstituted murine prostate grafts. Independently, iLRP5 induction in adult prostate stroma enhanced prostate tissue regeneration. Moreover, induction of iLRP5 in male Ubi-Cat mice resulted in prostate tumor progression over several months from prostate hyperplasia to adenocarcinoma. We also investigated iLRP5 activation in Ubi-Cat-derived mammary cells, observing that prolonged activation results in mammary tumor formation. Thus, in two distinct experimental mouse models, activation of iLRP5 results in disruption of tissue homeostasis, demonstrating the utility of iLRP5 as a novel research tool for determining the outcome of Wnt activation in a precise spatially and temporally determined fashion.

  3. Wnt signaling underlies evolution and development of the butterfly wing pattern symmetry systems.

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    Martin, Arnaud; Reed, Robert D

    2014-11-15

    Most butterfly wing patterns are proposed to be derived from a set of conserved pattern elements known as symmetry systems. Symmetry systems are so-named because they are often associated with parallel color stripes mirrored around linear organizing centers that run between the anterior and posterior wing margins. Even though the symmetry systems are the most prominent and diverse wing pattern elements, their study has been confounded by a lack of knowledge regarding the molecular basis of their development, as well as the difficulty of drawing pattern homologies across species with highly derived wing patterns. Here we present the first molecular characterization of symmetry system development by showing that WntA expression is consistently associated with the major basal, discal, central, and external symmetry system patterns of nymphalid butterflies. Pharmacological manipulations of signaling gradients using heparin and dextran sulfate showed that pattern organizing centers correspond precisely with WntA, wingless, Wnt6, and Wnt10 expression patterns, thus suggesting a role for Wnt signaling in color pattern induction. Importantly, this model is supported by recent genetic and population genomic work identifying WntA as the causative locus underlying wing pattern variation within several butterfly species. By comparing the expression of WntA between nymphalid butterflies representing a range of prototypical symmetry systems, slightly deviated symmetry systems, and highly derived wing patterns, we were able to infer symmetry system homologies in several challenging cases. Our work illustrates how highly divergent morphologies can be derived from modifications to a common ground plan across both micro- and macro-evolutionary time scales. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. The Notch-2 gene is regulated by Wnt signaling in cultured colorectal cancer cells.

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    Jonas Ungerbäck

    Full Text Available BACKGROUND: Notch and Wnt pathways are key regulators of intestinal homeostasis and alterations in these pathways may lead to the development of colorectal cancer (CRC. In CRC the Apc/β-catenin genes in the Wnt signaling pathway are frequently mutated and active Notch signaling contributes to tumorigenesis by keeping the epithelial cells in a proliferative state. These pathways are simultaneously active in proliferative adenoma cells and a crosstalk between them has previously been suggested in normal development as well as in cancer. PRINCIPAL FINDINGS: In this study, in silico analysis of putative promoters involved in transcriptional regulation of genes coding for proteins in the Notch signaling pathway revealed several putative LEF-1/TCF sites as potential targets for β-catenin and canonical Wnt signaling. Further results from competitive electrophoretic mobility-shift assay (EMSA studies suggest binding of several putative sites in Notch pathway gene promoters to in vitro translated β-catenin/Lef-1. Wild type (wt-Apc negatively regulates β-catenin. By induction of wt-Apc or β-catenin silencing in HT29 cells, we observed that several genes in the Notch pathway, including Notch-2, were downregulated. Finally, active Notch signaling was verified in the Apc(Min/+ mouse model where Hes-1 mRNA levels were found significantly upregulated in intestinal tumors compared to normal intestinal mucosa. Luciferase assays showed an increased activity for the core and proximal Notch-2 promoter upon co-transfection of HCT116 cells with high expression recombinant Tcf-4, Lef-1 or β-catenin. CONCLUSIONS: In this paper, we identified Notch-2 as a novel target for β-catenin-dependent Wnt signaling. Furthermore our data supports the notion that additional genes in the Notch pathway might be transcriptionally regulated by Wnt signaling in colorectal cancer.

  5. An Lmx1b-miR135a2 regulatory circuit modulates Wnt1/Wnt signaling and determines the size of the midbrain dopaminergic progenitor pool.

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    Angela Anderegg

    Full Text Available MicroRNAs regulate gene expression in diverse physiological scenarios. Their role in the control of morphogen related signaling pathways has been less studied, particularly in the context of embryonic Central Nervous System (CNS development. Here, we uncover a role for microRNAs in limiting the spatiotemporal range of morphogen expression and function. Wnt1 is a key morphogen in the embryonic midbrain, and directs proliferation, survival, patterning and neurogenesis. We reveal an autoregulatory negative feedback loop between the transcription factor Lmx1b and a newly characterized microRNA, miR135a2, which modulates the extent of Wnt1/Wnt signaling and the size of the dopamine progenitor domain. Conditional gain of function studies reveal that Lmx1b promotes Wnt1/Wnt signaling, and thereby increases midbrain size and dopamine progenitor allocation. Conditional removal of Lmx1b has the opposite effect, in that expansion of the dopamine progenitor domain is severely compromised. Next, we provide evidence that microRNAs are involved in restricting dopamine progenitor allocation. Conditional loss of Dicer1 in embryonic stem cells (ESCs results in expanded Lmx1a/b+ progenitors. In contrast, forced elevation of miR135a2 during an early window in vivo phenocopies the Lmx1b conditional knockout. When En1::Cre, but not Shh::Cre or Nes::Cre, is used for recombination, the expansion of Lmx1a/b+ progenitors is selectively reduced. Bioinformatics and luciferase assay data suggests that miR135a2 targets Lmx1b and many genes in the Wnt signaling pathway, including Ccnd1, Gsk3b, and Tcf7l2. Consistent with this, we demonstrate that this mutant displays reductions in the size of the Lmx1b/Wnt1 domain and range of canonical Wnt signaling. We posit that microRNA modulation of the Lmx1b/Wnt axis in the early midbrain/isthmus could determine midbrain size and allocation of dopamine progenitors. Since canonical Wnt activity has recently been recognized as a key

  6. Secreted Wnt Signaling Inhibitors in Disuse-Induced Bone Loss

    Science.gov (United States)

    2014-07-01

    other peripheral nerve injuries that  induce  paralysis.  Disuse  osteoporosis  is a com‐ mon sequelae of spinal cord injury (SCI) an peripheral nerve damage...AND SUBTITLE Secreted Wnt inhibitors in disuse- induced bone loss 5a. CONTRACT NUMBER 5b. GRANT NUMBER 6. AUTHOR(S) Alexander G. Robling, PhD...preventing paralysis- induced bone loss. In the first series, adult female mice were subjected to unilateral Botox- induced muscle paralysis of the

  7. Early Transcriptional Changes Induced by Wnt/β-Catenin Signaling in Hippocampal Neurons

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    Eduardo Pérez-Palma

    2016-01-01

    Full Text Available Wnt/β-catenin signaling modulates brain development and function and its deregulation underlies pathological changes occurring in neurodegenerative and neurodevelopmental disorders. Since one of the main effects of Wnt/β-catenin signaling is the modulation of target genes, in the present work we examined global transcriptional changes induced by short-term Wnt3a treatment (4 h in primary cultures of rat hippocampal neurons. RNAseq experiments allowed the identification of 170 differentially expressed genes, including known Wnt/β-catenin target genes such as Notum, Axin2, and Lef1, as well as novel potential candidates Fam84a, Stk32a, and Itga9. Main biological processes enriched with differentially expressed genes included neural precursor (GO:0061364, p-adjusted = 2.5 × 10−7, forebrain development (GO:0030900, p-adjusted = 7.3 × 10−7, and stem cell differentiation (GO:0048863 p-adjusted = 7.3 × 10−7. Likewise, following activation of the signaling cascade, the expression of a significant number of genes with transcription factor activity (GO:0043565, p-adjusted = 4.1 × 10−6 was induced. We also studied molecular networks enriched upon Wnt3a activation and detected three highly significant expression modules involved in glycerolipid metabolic process (GO:0046486, p-adjusted = 4.5 × 10−19, learning or memory (GO:0007611, p-adjusted = 4.0 × 10−5, and neurotransmitter secretion (GO:0007269, p-adjusted = 5.3 × 10−12. Our results indicate that Wnt/β-catenin mediated transcription controls multiple biological processes related to neuronal structure and activity that are affected in synaptic dysfunction disorders.

  8. Genotoxic exposure during juvenile growth of mammary gland depletes stem cell activity and inhibits Wnt signaling.

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    Kristine S Klos

    Full Text Available Various types of somatic stem cell have been tested for their response to genotoxic exposure, since these cells are likely to be important to regeneration, aging and cancer. In this study, we evaluated the response of mammary stem cells to genotoxic exposure during ductal growth in juveniles. Exposure to the polycyclic aromatic hydrocarbon (DMBA; 7,12 dimethylbenz[a]anthracene had no gross effect on outgrowth and morphogenesis of the ductal tree, or upon lobuloalveolar growth during pregnancy. However, by fat pad assay, we found that mammary stem cell activity was reduced by 80% in glands from adults that were exposed to genotoxins as juveniles. The associated basal cell lineage was depleted. Both basal and luminal cells showed a robust response to genotoxic exposure (including γH2AX phosphorylation, pS(15p53 and pT(68Chk2, with durable hyperproliferation, but little cytotoxicity. Since the phenotype of these glands (low basal cell fraction, low stem cell activity phenocopies mammary glands with loss of function for Wnt signaling, we measured Wnt signaling in genotoxin-exposed glands, and found a durable reduction in the activation of the canonical signaling Wnt receptors, Lrp5/6. Furthermore, when mammary epithelial cells were treated with Wnt3a, DMBA exposure reduced the basal cell population and Lrp activation was ablated. We conclude that during active ductal growth, Wnt-dependent mammary stem cells are sensitized to cell death by genotoxin exposure. Our conclusion may be important for other tissues, since all solid tumor stem cell activities have been shown to be Wnt-dependent to date.

  9. The canonical Wnt signaling pathway plays an important role in lymphopoiesis and hematopoiesis

    NARCIS (Netherlands)

    F.J.T. Staal (Frank); J.M. Sen (Jyoti Misra)

    2008-01-01

    textabstractThe evolutionarily conserved canonical Wnt-β-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

  10. The role of the Wnt signaling pathway in cancer stem cells: prospects for drug development.

    Science.gov (United States)

    Kim, Yong-Mi; Kahn, Michael

    Cancer stem cells (CSCs), also known as tumor initiating cells are now considered to be the root cause of most if not all cancers, evading treatment and giving rise to disease relapse. They have become a central focus in new drug development. Prospective identification, understanding the key pathways that maintain CSCs, and being able to target CSCs, particularly if the normal stem cell population could be spared, could offer an incredible therapeutic advantage. The Wnt signaling cascade is critically important in stem cell biology, both in homeostatic maintenance of tissues and organs through their respective somatic stem cells and in the CSC/tumor initiating cell population. Aberrant Wnt signaling is associated with a wide array of tumor types. Therefore, the ability to safely target the Wnt signaling pathway offers enormous promise to target CSCs. However, just like the sword of Damocles, significant risks and concerns regarding targeting such a critical pathway in normal stem cell maintenance and tissue homeostasis remain ever present. With this in mind, we review recent efforts in modulating the Wnt signaling cascade and critically analyze therapeutic approaches at various stages of development.

  11. Epigenetic Activation of Wnt/β-Catenin Signaling in NAFLD-Associated Hepatocarcinogenesis

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    Yuan Tian

    2016-08-01

    Full Text Available Non-alcoholic fatty liver disease (NAFLD, characterized by fat accumulation in liver, is closely associated with central obesity, over-nutrition and other features of metabolic syndrome, which elevate the risk of developing hepatocellular carcinoma (HCC. The Wnt/β-catenin signaling pathway plays a significant role in the physiology and pathology of liver. Up to half of HCC patients have activation of Wnt/β-catenin signaling. However, the mutation frequencies of CTNNB1 (encoding β-catenin protein or other antagonists targeting Wnt/β-catenin signaling are low in HCC patients, suggesting that genetic mutations are not the major factor driving abnormal β-catenin activities in HCC. Emerging evidence has demonstrated that obesity-induced metabolic pathways can deregulate chromatin modifiers such as histone deacetylase 8 to trigger undesired global epigenetic changes, thereby modifying gene expression program which contributes to oncogenic signaling. This review focuses on the aberrant epigenetic activation of Wnt/β-catenin in the development of NAFLD-associated HCC. A deeper understanding of the molecular mechanisms underlying such deregulation may shed light on the identification of novel druggable epigenetic targets for the prevention and/or treatment of HCC in obese and diabetic patients.

  12. Epigenetic Activation of Wnt/β-Catenin Signaling in NAFLD-Associated Hepatocarcinogenesis.

    Science.gov (United States)

    Tian, Yuan; Mok, Myth T S; Yang, Pengyuan; Cheng, Alfred S L

    2016-08-20

    Non-alcoholic fatty liver disease (NAFLD), characterized by fat accumulation in liver, is closely associated with central obesity, over-nutrition and other features of metabolic syndrome, which elevate the risk of developing hepatocellular carcinoma (HCC). The Wnt/β-catenin signaling pathway plays a significant role in the physiology and pathology of liver. Up to half of HCC patients have activation of Wnt/β-catenin signaling. However, the mutation frequencies of CTNNB1 (encoding β-catenin protein) or other antagonists targeting Wnt/β-catenin signaling are low in HCC patients, suggesting that genetic mutations are not the major factor driving abnormal β-catenin activities in HCC. Emerging evidence has demonstrated that obesity-induced metabolic pathways can deregulate chromatin modifiers such as histone deacetylase 8 to trigger undesired global epigenetic changes, thereby modifying gene expression program which contributes to oncogenic signaling. This review focuses on the aberrant epigenetic activation of Wnt/β-catenin in the development of NAFLD-associated HCC. A deeper understanding of the molecular mechanisms underlying such deregulation may shed light on the identification of novel druggable epigenetic targets for the prevention and/or treatment of HCC in obese and diabetic patients.

  13. Epsin is required for Dishevelled stability and Wnt signalling activation in colon cancer development.

    Science.gov (United States)

    Chang, Baojun; Tessneer, Kandice L; McManus, John; Liu, Xiaolei; Hahn, Scott; Pasula, Satish; Wu, Hao; Song, Hoogeun; Chen, Yiyuan; Cai, Xiaofeng; Dong, Yunzhou; Brophy, Megan L; Rahman, Ruby; Ma, Jian-Xing; Xia, Lijun; Chen, Hong

    2015-03-16

    Uncontrolled canonical Wnt signalling supports colon epithelial tumour expansion and malignant transformation. Understanding the regulatory mechanisms involved is crucial for elucidating the pathogenesis of and will provide new therapeutic targets for colon cancer. Epsins are ubiquitin-binding adaptor proteins upregulated in several human cancers; however, the involvement of epsins in colon cancer is unknown. Here we show that loss of intestinal epithelial epsins protects against colon cancer by significantly reducing the stability of the crucial Wnt signalling effector, dishevelled (Dvl2), and impairing Wnt signalling. Consistently, epsins and Dvl2 are correspondingly upregulated in colon cancer. Mechanistically, epsin binds Dvl2 via its epsin N-terminal homology domain and ubiquitin-interacting motifs and prohibits Dvl2 polyubiquitination and degradation. Our findings reveal an unconventional role for epsins in stabilizing Dvl2 and potentiating Wnt signalling in colon cancer cells to ensure robust colon cancer progression. The pro-carcinogenic role of Epsins suggests that they are potential therapeutic targets to combat colon cancer.

  14. SMAD4-mediated WNT signaling controls the fate of cranial neural crest cells during tooth morphogenesis

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    Li, Jingyuan; Huang, Xiaofeng; Xu, Xun; Mayo, Julie; Bringas, Pablo; Jiang, Rulang; Wang, Songling; Chai, Yang

    2011-01-01

    TGFβ/BMP signaling regulates the fate of multipotential cranial neural crest (CNC) cells during tooth and jawbone formation as these cells differentiate into odontoblasts and osteoblasts, respectively. The functional significance of SMAD4, the common mediator of TGFβ/BMP signaling, in regulating the fate of CNC cells remains unclear. In this study, we investigated the mechanism of SMAD4 in regulating the fate of CNC-derived dental mesenchymal cells through tissue-specific inactivation of Smad4. Ablation of Smad4 results in defects in odontoblast differentiation and dentin formation. Moreover, ectopic bone-like structures replaced normal dentin in the teeth of Osr2-IresCre;Smad4fl/fl mice. Despite the lack of dentin, enamel formation appeared unaffected in Osr2-IresCre;Smad4fl/fl mice, challenging the paradigm that the initiation of enamel development depends on normal dentin formation. At the molecular level, loss of Smad4 results in downregulation of the WNT pathway inhibitors Dkk1 and Sfrp1 and in the upregulation of canonical WNT signaling, including increased β-catenin activity. More importantly, inhibition of the upregulated canonical WNT pathway in Osr2-IresCre;Smad4fl/fl dental mesenchyme in vitro partially rescued the CNC cell fate change. Taken together, our study demonstrates that SMAD4 plays a crucial role in regulating the interplay between TGFβ/BMP and WNT signaling to ensure the proper CNC cell fate decision during organogenesis. PMID:21490069

  15. Wnt/β-catenin signaling in adult mammalian epithelial stem cells

    NARCIS (Netherlands)

    Kretzschmar, Kai; Clevers, Hans

    2017-01-01

    Adult stem cells self-renew and replenish differentiated cells in various organs and tissues throughout a mammal's life. Over the last 25 years an ever-growing body of knowledge has unraveled the essential regulation of adult mammalian epithelia by the canonical Wnt signaling with its key

  16. New advances of TMEM88 in cancer initiation and progression, with special emphasis on Wnt signaling pathway.

    Science.gov (United States)

    Ge, Yun-Xuan; Wang, Chang-Hui; Hu, Fu-Yong; Pan, Lin-Xin; Min, Jie; Niu, Kai-Yuan; Zhang, Lei; Li, Jun; Xu, Tao

    2018-01-01

    Transmembrane protein 88 (TMEM88), a newly discovered protein localized on the cell membrane. Recent studies showed that TMEM88 was involved in the regulation of several types of cancer. TMEM88 was expressed at significantly higher levels in breast cancer (BC) cell line than in normal breast cell line with co-localized with Dishevelled (DVL) in the cytoplasm of BC cell line. TMEM88 silencing in the ovarian cancer cell line CP70 resulted in significant upregulation of Wnt downstream genes (c-Myc, cyclin-D1) and other Wnt target genes including JUN, PTIX2, CTNNB1 (β-catenin), further supporting that TMEM88 inhibits canonical Wnt signaling pathway. Wnt signaling pathway has been known to play important roles in many diseases, especially in cancer. For instance, hepatocellular carcinoma (HCC) has become one of the most common tumors harboring mutations in the Wnt signaling pathway. As the inhibitor of Wnt signaling, TMEM88 has been considered to act as an oncogene or a tumor suppressor. Up-regulated TMEM88 or gene therapy approaches could be an effective therapeutic approach against tumor as TMEM88 inhibits Wnt signaling through direct interaction with DVL. Here, we review the current knowledge on the functional role and potential clinical application of TMEM88 in the control of various cancers. Highlights Wnt signaling displays an important role in several pathogenesis of cancer. Wnt signaling pathway is activated during cancer development. TMEM88 has an impact on cancer by inhibiting canonical Wnt signaling. We discuss the importance and new applications of TMEM88 in cancer therapy. © 2017 Wiley Periodicals, Inc.

  17. The involvement of lethal giant larvae and Wnt signaling in bottle cell formation in Xenopus embryos

    OpenAIRE

    Choi, Sun-Cheol; Sokol, Sergei Y.

    2009-01-01

    Lethal giant larvae (Lgl) plays a critical role in establishment of cell polarity in epithelial cells. While Frizzled/Dsh signaling has been implicated in the regulation of the localization and activity of Lgl, it remains unclear whether specific Wnt ligands are involved. Here we show that Wnt5a triggers the release of Lgl from the cell cortex into the cytoplasm with the concomitant decrease in Lgl stability. The observed changes in Lgl localization were independent of atypical PKC (aPKC), wh...

  18. Wnt signaling positively regulates endothelial cell fate specification in the Fli1a-positive progenitor population via Lef1.

    Science.gov (United States)

    Hübner, Kathleen; Grassme, Kathrin S; Rao, Jyoti; Wenke, Nina K; Zimmer, Cordula L; Korte, Laura; Mu Ller, Katja; Sumanas, Saulius; Greber, Boris; Herzog, Wiebke

    2017-10-01

    During vertebrate embryogenesis, vascular endothelial cells (ECs) and primitive erythrocytes become specified within close proximity in the posterior lateral plate mesoderm (LPM) from a common progenitor. However, the signaling cascades regulating the specification into either lineage remain largely elusive. Here, we analyze the contribution of β-catenin dependent Wnt signaling to EC and erythrocyte specification during zebrafish embryogenesis. We generated novel β-catenin dependent Wnt signaling reporters which, by using destabilized fluorophores (Venus-Pest, dGFP), specifically allow us to detect Wnt signaling responses in narrow time windows as well as in spatially restricted domains, defined by Cre recombinase expression (Tg(axin2 BAC :Venus-Pest) mu288 ; Tg(14TCF:loxP-STOP-loxP-dGFP) mu202 ). We therefore can detect β-catenin dependent Wnt signaling activity in a subset of the Fli1a-positive progenitor population. Additionally, we show that mesodermal Wnt3a-mediated signaling via the transcription factor Lef1 positively regulates EC specification (defined by kdrl expression) at the expense of primitive erythrocyte specification (defined by gata1 expression) in zebrafish embryos. Using mesoderm derived from human embryonic stem cells, we identified the same principle of Wnt signaling dependent EC specification in conjunction with auto-upregulation of LEF1. Our data indicate a novel role of β-catenin dependent Wnt signaling in regulating EC specification during vasculogenesis. Copyright © 2017. Published by Elsevier Inc.

  19. Novel Mutation of LRP6 Identified in Chinese Han Population Links Canonical WNT Signaling to Neural Tube Defects.

    Science.gov (United States)

    Shi, Zhiwen; Yang, Xueyan; Li, Bin-Bin; Chen, Shuxia; Yang, Luming; Cheng, Liangping; Zhang, Ting; Wang, Hongyan; Zheng, Yufang

    2017-09-29

    Neural tube defects (NTDs), the second most frequent cause of human congenital abnormalities, are debilitating birth defects due to failure of neural tube closure. It has been shown that noncanonical WNT/planar cell polarity (PCP) signaling is required for convergent extension (CE), the initiation step of neural tube closure (NTC). But the effect of canonical WNT//β-catenin signaling during NTC is still elusive. LRP6 (low density lipoprotein receptor related proteins 6) was identified as a co-receptor for WNT/β-catenin signaling, but recent studies showed that it also can mediate WNT/PCP signaling. In this study, we screened mutations in the LRP6 gene in 343 NTDs and 215 ethnically matched normal controls of Chinese Han population. Three rare missense mutations (c.1514A>G, p.Y505C); c.2984A>G, p.D995G; and c.4280C>A, p.P1427Q) of the LRP6 gene were identified in Chinese NTD patients. The Y505C mutation is a loss-of-function mutation on both WNT/β-catenin and PCP signaling. The D995G mutation only partially lost inhibition on PCP signaling without affecting WNT/β-catenin signaling. The P1427Q mutation dramatically increased WNT/β-catenin signaling but only mildly loss of inhibition on PCP signaling. All three mutations failed to rescue CE defects caused by lrp6 morpholino oligos knockdown in zebrafish. Of interest, when overexpressed, D995G did not induce any defects, but Y505C and P1427Q caused more severe CE defects in zebrafish. Our results suggested that over-active canonical WNT signaling induced by gain-of-function mutation in LRP6 could also contribute to human NTDs, and a balanced WNT/β-catenin and PCP signaling is probably required for proper neural tube development. Birth Defects Research, 2017.© 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  20. Discrete somatic niches coordinate proliferation and migration of primordial germ cells via Wnt signaling.

    Science.gov (United States)

    Cantú, Andrea V; Altshuler-Keylin, Svetlana; Laird, Diana J

    2016-07-18

    Inheritance depends on the expansion of a small number of primordial germ cells (PGCs) in the early embryo. Proliferation of mammalian PGCs is concurrent with their movement through changing microenvironments; however, mechanisms coordinating these conflicting processes remain unclear. Here, we find that PGC proliferation varies by location rather than embryonic age. Ror2 and Wnt5a mutants with mislocalized PGCs corroborate the microenvironmental regulation of the cell cycle, except in the hindgut, where Wnt5a is highly expressed. Molecular and genetic evidence suggests that Wnt5a acts via Ror2 to suppress β-catenin-dependent Wnt signaling in PGCs and limit their proliferation in specific locations, which we validate by overactivating β-catenin in PGCs. Our results suggest that the balance between expansion and movement of migratory PGCs is fine-tuned in different niches by the opposing β-catenin-dependent and Ror2-mediated pathways through Wnt5a This could serve as a selective mechanism to favor early and efficient migrators with clonal dominance in the ensuing germ cell pool while penalizing stragglers. © 2016 Cantú et al.

  1. β-TrCP1 Is a Vacillatory Regulator of Wnt Signaling.

    Science.gov (United States)

    Long, Marcus John; Lin, Hong-Yu; Parvez, Saba; Zhao, Yi; Poganik, Jesse Richard; Huang, Paul; Aye, Yimon

    2017-08-17

    Simultaneous hyperactivation of Wnt and antioxidant response (AR) are often observed during oncogenesis. However, it remains unclear how the β-catenin-driven Wnt and the Nrf2-driven AR mutually regulate each other. The situation is compounded because many players in these two pathways are redox sensors, rendering bolus redox signal-dosing methods uninformative. Herein we examine the ramifications of single-protein target-specific AR upregulation in various knockdown lines. Our data document that Nrf2/AR strongly inhibits β-catenin/Wnt. The magnitude and mechanism of this negative regulation are dependent on the direct interaction between β-catenin N terminus and β-TrCP1 (an antagonist of both Nrf2 and β-catenin), and independent of binding between Nrf2 and β-TrCP1. Intriguingly, β-catenin positively regulates AR. Because AR is a negative regulator of Wnt regardless of β-catenin N terminus, this switch of function is likely sufficient to establish a new Wnt/AR equilibrium during tumorigenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. WNT signaling controls expression of pro-apoptotic BOK and BAX in intestinal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zeilstra, Jurrit; Joosten, Sander P.J. [Department of Pathology, Academic Medical Center, University of Amsterdam (Netherlands); Wensveen, Felix M. [Department of Experimental Immunology, Academic Medical Center, Amsterdam (Netherlands); Dessing, Mark C.; Schuetze, Denise M. [Department of Pathology, Academic Medical Center, University of Amsterdam (Netherlands); Eldering, Eric [Department of Experimental Immunology, Academic Medical Center, Amsterdam (Netherlands); Spaargaren, Marcel [Department of Pathology, Academic Medical Center, University of Amsterdam (Netherlands); Pals, Steven T., E-mail: s.t.pals@amc.uva.nl [Department of Pathology, Academic Medical Center, University of Amsterdam (Netherlands)

    2011-03-04

    Research highlights: {yields} Intestinal adenomas initiated by aberrant activation of the WNT pathway displayed an increased sensitivity to apoptosis. {yields} Expression profiling of apoptosis-related genes in Apc{sup Min/+} mice revealed the differential expression of pro-apoptotic Bok and Bax. {yields} APC-mutant adenomatous crypts in FAP patients showed strongly increased BAX immunoreactivity. {yields} Blocking of {beta}-catenin/TCF-4-mediated signaling in colon cancer cells reduced the expression of BOK and BAX. -- Abstract: In a majority of cases, colorectal cancer is initiated by aberrant activation of the WNT signaling pathway. Mutation of the genes encoding the WNT signaling components adenomatous polyposis coli or {beta}-catenin causes constitutively active {beta}-catenin/TCF-mediated transcription, driving the transformation of intestinal crypts to cancer precursor lesions, called dysplastic aberrant crypt foci. Deregulated apoptosis is a hallmark of adenomatous colon tissue. However, the contribution of WNT signaling to this process is not fully understood. We addressed this role by analyzing the rate of epithelial apoptosis in aberrant crypts and adenomas of the Apc{sup Min/+} mouse model. In comparison with normal crypts and adenomas, aberrant crypts displayed a dramatically increased rate of apoptotic cell death. Expression profiling of apoptosis-related genes along the crypt-villus axis and in Apc mutant adenomas revealed increased expression of two pro-apoptotic Bcl-2 family members in intestinal adenomas, Bok and Bax. Analysis of the colon of familial adenomatous polyposis (FAP) patients along the crypt-to-surface axis, and of dysplastic crypts, corroborated this expression pattern. Disruption of {beta}-catenin/TCF-4-mediated signaling in the colorectal cancer cell line Ls174T significantly decreased BOK and BAX expression, confirming WNT-dependent regulation in intestinal epithelial cells. Our results suggest a feedback mechanism by which

  3. Anteroposterior Patterning of Gene Expression in the Human Infant Sclera: Chondrogenic Potential and Wnt Signaling.

    Science.gov (United States)

    Seko, Yuko; Azuma, Noriyuki; Yokoi, Tadashi; Kami, Daisuke; Ishii, Ryuga; Nishina, Sachiko; Toyoda, Masashi; Shimokawa, Hitoyata; Umezawa, Akihiro

    2017-01-01

    Purpose/Aim: We sought to identify the anteroposterior spatial gene expression hierarchy in the human sclera to develop a hypothesis for axial elongation and deformity of the eyeball. We analyzed the global gene expression of human scleral cells derived from distinct parts of the human infant sclera obtained from surgically enucleated eyes with retinoblastoma, using Affymetrix GeneChip oligonucleotide arrays, and compared, in particular, gene expression levels between the anterior and posterior parts of the sclera. The ages of three donors were 10M, 4M, and 1Y9M. K-means clustering analysis of gene expression revealed that expression levels of cartilage-associated genes such as COLXIA and ACAN increased from the anterior to the posterior part of the sclera. Microarray analyses and RT-PCR data showed that the expression levels of MGP, COLXIA, BMP4, and RARB were significantly higher in the posterior than in the anterior sclera of two independent infant eyes. Conversely, expression levels of WNT2, DKK2, GREM1, and HOXB2 were significantly higher in the anterior sclera. Among several Wnt-family genes examined, WNT2B was found to be expressed at a significantly higher level in the posterior sclera, and the reverse order was observed for WNT2. The results of luciferase reporter assays suggested that a GSK-3β inhibitor stimulated Wnt/β-catenin signaling particularly strongly in the posterior sclera. The expression pattern of RARB, a myopia-related gene, was similar in three independent eyes. Chondrogenic potential was higher and Wnt/β-catenin signaling was more potently activated by a GSK-3β inhibitor in the posterior than in the anterior part of the human infant sclera. Although the differences in the gene expression profiles between the anterior and posterior sclera might be involved only in normal growth processes, this anteroposterior hierarchy in the sclera might contribute to disorders involving abnormal elongation and deformity of the eyeball, including myopia.

  4. Hyaluronic acid enhances proliferation of human amniotic mesenchymal stem cells through activation of Wnt/β-catenin signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ru-Ming; Sun, Ren-Gang; Zhang, Ling-Tao; Zhang, Qing-Fang; Chen, Dai-Xiong [Guizhou Center for Translational Medicine, Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi 563000 (China); Zhong, Jian-Jiang, E-mail: jjzhong@sjtu.edu.cn [State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240 (China); Xiao, Jian-Hui, E-mail: jhxiao@yahoo.com [Guizhou Center for Translational Medicine, Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi 563000 (China)

    2016-07-15

    This study investigated the pro-proliferative effect of hyaluronic acid (HA) on human amniotic mesenchymal stem cells (hAMSCs) and the underlying mechanisms. Treatment with HA increased cell population growth in a dose- and time-dependent manner. Analyses by flow cytometry and immunocytochemistry revealed that HA did not change the cytophenotypes of hAMSCs. Additionally, the osteogenic, chondrogenic, and adipogenic differentiation capabilities of these hAMSCs were retained after HA treatment. Moreover, HA increased the mRNA expressions of wnt1, wnt3a, wnt8a, cyclin D1, Ki-67, and β-catenin as well as the protein level of β-catenin and cyclin D1 in hAMSCs; and the nuclear localization of β-catenin was also enhanced. Furthermore, the pro-proliferative effect of HA and up-regulated expression of Wnt/β-catenin pathway-associated proteins - wnt3a, β-catenin and cyclin D1 in hAMSCs were significantly inhibited upon pre-treatment with Wnt-C59, an inhibitor of the Wnt/β-catenin pathway. These results suggest that HA may positively regulate hAMSCs proliferation through regulation of the Wnt/β-catenin signaling pathway. - Highlights: • Hyaluronic acid (HA) could promote the proliferation of hAMSCs. • HA treatment dose not affect the pluripotency of hAMSCs. • HA increases hAMSCs proliferation through activation of Wnt/β-catenin signaling.

  5. New Insights into Wnt-Lrp5/6-β-Catenin Signaling in Mechanotransduction.

    Science.gov (United States)

    Kang, Kyung Shin; Robling, Alexander G

    2014-01-01

    Mechanical loading is essential to maintain normal bone metabolism and the balance between bone formation and resorption. The cellular mechanisms that control mechanotransduction are not fully defined, but several key pathways have been identified. We discuss the roles of several components of the Wnt signaling cascade, namely Lrp5, Lrp6, and β-catenin in mechanical loading-induced bone formation. Lrp5 is an important Wnt co-receptor for regulating bone mass and mechanotransduction, and appears to function principally by augmenting bone formation. Lrp6 also regulates bone mass but its action might involve resorption as well as formation. The role of Lrp6 in mechanotransduction is unclear. Studies addressing the role of β-catenin in bone metabolism and mechanotransduction highlight the uncertainties in downstream modulators of Lrp5 and Lrp6. Taken together, these data indicate that mechanical loading might affect bone regulation triggering the canonical Wnt signaling (and perhaps other pathways) not only via Lrp5 but also via Lrp6. Further work is needed to clarify the role of the Wnt signaling pathway in Lrp5 and/or Lrp6-mediated mechanotransduction, which could eventually lead to powerful therapeutic agents that might mimic the anabolic effects of mechanical stimulation.

  6. Molecular Genetics of Intracranial Meningiomas with Emphasis on Canonical Wnt Signalling

    Directory of Open Access Journals (Sweden)

    Nives Pećina-Šlaus

    2016-07-01

    Full Text Available Research over the last decade recognized the importance of novel molecular pathways in pathogenesis of intracranial meningiomas. In this review, we focus on human brain tumours meningiomas and the involvement of Wnt signalling pathway genes and proteins in this common brain tumour, describing their known functional effects. Meningiomas originate from the meningeal layers of the brain and the spinal cord. Most meningiomas have benign clinical behaviour and are classified as grade I by World Health Organization (WHO. However, up to 20% histologically classified as atypical (grade II or anaplastic (grade III are associated with higher recurrent rate and have overall less favourable clinical outcome. Recently, there is emerging evidence that multiple signalling pathways including Wnt pathway contribute to the formation and growth of meningiomas. In the review we present the synopsis on meningioma histopathology and genetics and discuss our research regarding Wnt in meningioma. Epithelial-to-mesenchymal transition, a process in which Wnt signalling plays an important role, is shortly discussed.

  7. Wnt signaling induces differentiation of progenitor cells in organotypic keratinocyte cultures

    Directory of Open Access Journals (Sweden)

    Liu Bob Y

    2007-02-01

    Full Text Available Abstract Background Interfollicular skin develops normally only when the activity of the progenitor cells in the basal layer is counterbalanced by the exit of cells into the suprabasal layers, where they differentiate and cornify to establish barrier function. Distinct stem and progenitor compartments have been demonstrated in hair follicles and sebaceous glands, but there are few data to describe the control of interfollicular progenitor cell activity. Wnt signaling has been shown to be an important growth-inducer of stem cell compartments in skin and many other tissues. Results Here, we test the effect of ectopic Wnt1 expression on the behavior of interfollicular progenitor cells in an organotypic culture model, and find that Wnt1 signaling inhibits their growth and promotes terminal differentiation. Conclusion These results are consistent with the phenotypes reported for transgenic mice engineered to have gain or loss of function of Wnt signaling in skin, which would recommend our culture model as an accurate one for molecular analysis. Since it is known that canonical ligands are expressed in skin, it is likely that this pathway normally regulates the balance of growth and differentiation, and suggests it could be important to pathogenesis.

  8. New insights into Wnt - Lrp5/6 - β-catenin signaling in mechanotransduction

    Directory of Open Access Journals (Sweden)

    Alexander eRobling

    2015-01-01

    Full Text Available Mechanical loading is essential to maintain normal bone metabolism and the balance between bone formation and resorption. The cellular mechanisms that control mechanotransduction are not fully defined, but several key pathways have been identified. We discuss the roles of several components of the Wnt signaling cascade, namely Lrp5, Lrp6, and β-catenin in mechanical loading-induced bone formation. Lrp5 is an important Wnt co-receptor for regulating bone mass and mechanotransduction, and appears to function principally by augmenting bone formation. Lrp6 also regulates bone mass but its action might involve resorption as well as formation. The role of Lrp6 in mechanotransduction is unclear. Studies addressing the role of β-catenin in bone metabolism and mechanotransduction highlight the uncertainties in downstream modulators of Lrp5 and Lrp6. Taken together, these data indicate that mechanical loading might affect bone regulation triggering the canonical Wnt signaling (and perhaps other pathways not only via Lrp5 but also via Lrp6. Further work is needed to clarify the role of the Wnt signaling pathway in Lrp5 and/or Lrp6-mediated mechanotransduction, which could eventually lead to powerful therapeutic agents that might mimic the anabolic effects of mechanical stimulation.

  9. Pigment Epithelium-Derived Factor (PEDF Inhibits Wnt/β-catenin Signaling in the LiverSummary

    Directory of Open Access Journals (Sweden)

    Petr Protiva

    2015-09-01

    Full Text Available Background & Aims: Pigment epithelium-derived factor (PEDF is a secretory protein that inhibits multiple tumor types. PEDF inhibits the Wnt coreceptor, low-density lipoprotein receptor-related protein 6 (LRP6, in the eye, but whether the tumor-suppressive properties of PEDF occur in organs such as the liver is unknown. Methods: Wnt-dependent regulation of PEDF was assessed in the absence and presence of the Wnt coreceptor LRP6. Whole genome expression analysis was performed on PEDF knockout (KO and control livers (7 months. Interrogation of Wnt/β-catenin signaling was performed in whole livers and human hepatocellular carcinoma (HCC cell lines after RNA interference of PEDF and restoration of a PEDF-derived peptide. Western diet feeding for 6 to 8 months was used to evaluate whether the absence of PEDF was permissive for HCC formation (n = 12/group. Results: PEDF levels increased in response to canonical Wnt3a in an LRP6-dependent manner but were suppressed by noncanonical Wnt5a protein in an LRP6-independent manner. Gene set enrichment analysis (GSEA of PEDF KO livers revealed induction of pathways associated with experimental and human HCC and a transcriptional profile characterized by Wnt/β-catenin activation. Enhanced Wnt/β-catenin signaling occurred in KO livers, and PEDF delivery in vivo reduced LRP6 activation. In human HCC cells, RNA interference of PEDF led to increased levels of activated LRP6 and β-catenin, and a PEDF 34-mer peptide decreased LRP6 activation and β-catenin signaling, and reduced Wnt target genes. PEDF KO mice fed a Western diet developed sporadic well-differentiated HCC. Human HCC specimens demonstrated decreased PEDF staining compared with hepatocytes. Conclusions: PEDF is an endogenous inhibitor of Wnt/β-catenin signaling in the liver. Keywords: Extracellular Matrix, PEDF, Wnt/β-Catenin

  10. Ganoderma lucidum (Reishi) suppresses proliferation and migration of breast cancer cells via inhibiting Wnt/β-catenin signaling.

    Science.gov (United States)

    Zhang, Yu

    2017-07-08

    The medical mushroom Ganoderma lucidum (Reishi), a traditional Chinese medicine, has exhibited a promising anti-cancer effect. However, the molecular mechanism of its action on cancer cells remains unclear. Aberrant activation of Wnt/β-catenin signaling pathway is the cause of many types of cancer, including breast cancer. Here we investigated the effect of Reishi on Wnt/β-catenin signaling pathway and elucidated the molecular mechanism of its function in inhibiting breast cancer cells. We found that Reishi blocked Wnt/β-catenin signaling through inhibiting the phosphorylation of Wnt co-receptor LRP6. In human (MDA-MB-231) and mouse (4T1) breast cancer cell lines, Reishi significantly decreased the phosphorylation of LRP6 and suppressed Wnt3a-activated Wnt target gene Axin2 expression. Administration of Reishi inhibited Wnt-induced hyper-proliferation of breast cancer cells and MDA-MB-231 cell migration. Our results provide evidence that Reishi suppresses breast cancer cell growth and migration through inhibiting Wnt/β-catenin signaling, indicating that Reishi may be a potential natural inhibitor for breast cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Mutational analysis of sclerostin shows importance of the flexible loop and the cystine-knot for Wnt-signaling inhibition.

    Directory of Open Access Journals (Sweden)

    Verena Boschert

    Full Text Available The cystine-knot containing protein Sclerostin is an important negative regulator of bone growth and therefore represents a promising therapeutic target. It exerts its biological task by inhibiting the Wnt (wingless and int1 signaling pathway, which participates in bone formation by promoting the differentiation of mesenchymal stem cells to osteoblasts. The core structure of Sclerostin consists of three loops with the first and third loop (Finger 1 and Finger 2 forming a structured β-sheet and the second loop being unstructured and highly flexible. Biochemical data showed that the flexible loop is important for binding of Sclerostin to Wnt co-receptors of the low-density lipoprotein related-protein family (LRP, by interacting with the Wnt co-receptors LRP5 or -6 it inhibits Wnt signaling. To further examine the structural requirements for Wnt inhibition, we performed an extensive mutational study within all three loops of the Sclerostin core domain involving single and multiple mutations as well as truncation of important regions. By this approach we could confirm the importance of the second loop and especially of amino acids Asn92 and Ile94 for binding to LRP6. Based on a Sclerostin variant found in a Turkish family suffering from Sclerosteosis we generated a Sclerostin mutant with cysteines 84 and 142 exchanged thereby removing the third disulfide bond of the cystine-knot. This mutant binds to LRP6 with reduced binding affinity and also exhibits a strongly reduced inhibitory activity against Wnt1 thereby showing that also elements outside the flexible loop are important for inhibition of Wnt by Sclerostin. Additionally, we examined the effect of the mutations on the inhibition of two different Wnt proteins, Wnt3a and Wnt1. We could detect clear differences in the inhibition of these proteins, suggesting that the mechanism by which Sclerostin antagonizes Wnt1 and Wnt3a is fundamentally different.

  12. EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling.

    Science.gov (United States)

    Takeo, Makoto; Lee, Wendy; Rabbani, Piul; Sun, Qi; Hu, Hai; Lim, Chae Ho; Manga, Prashiela; Ito, Mayumi

    2016-05-10

    Delineating the crosstalk between distinct signaling pathways is key to understanding the diverse and dynamic responses of adult stem cells during tissue regeneration. Here, we demonstrate that the Edn/EdnrB signaling pathway can interact with other signaling pathways to elicit distinct stem cell functions during tissue regeneration. EdnrB signaling promotes proliferation and differentiation of melanocyte stem cells (McSCs), dramatically enhancing the regeneration of hair and epidermal melanocytes. This effect is dependent upon active Wnt signaling that is initiated by Wnt ligand secretion from the hair follicle epithelial niche. Further, this Wnt-dependent EdnrB signaling can rescue the defects in melanocyte regeneration caused by Mc1R loss. This suggests that targeting Edn/EdnrB signaling in McSCs can be a therapeutic approach to promote photoprotective-melanocyte regeneration, which may be useful for those with increased risk of skin cancers due to Mc1R variants. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Hyperactivated Wnt signaling induces synthetic lethal interaction with Rb inactivation by elevating TORC1 activities.

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    Tianyi Zhang

    2014-05-01

    Full Text Available Inactivation of the Rb tumor suppressor can lead to increased cell proliferation or cell death depending on specific cellular context. Therefore, identification of the interacting pathways that modulate the effect of Rb loss will provide novel insights into the roles of Rb in cancer development and promote new therapeutic strategies. Here, we identify a novel synthetic lethal interaction between Rb inactivation and deregulated Wg/Wnt signaling through unbiased genetic screens. We show that a weak allele of axin, which deregulates Wg signaling and increases cell proliferation without obvious effects on cell fate specification, significantly alters metabolic gene expression, causes hypersensitivity to metabolic stress induced by fasting, and induces synergistic apoptosis with mutation of fly Rb ortholog, rbf. Furthermore, hyperactivation of Wg signaling by other components of the Wg pathway also induces synergistic apoptosis with rbf. We show that hyperactivated Wg signaling significantly increases TORC1 activity and induces excessive energy stress with rbf mutation. Inhibition of TORC1 activity significantly suppressed synergistic cell death induced by hyperactivated Wg signaling and rbf inactivation, which is correlated with decreased energy stress and decreased induction of apoptotic regulator expression. Finally the synthetic lethality between Rb and deregulated Wnt signaling is conserved in mammalian cells and that inactivation of Rb and APC induces synergistic cell death through a similar mechanism. These results suggest that elevated TORC1 activity and metabolic stress underpin the evolutionarily conserved synthetic lethal interaction between hyperactivated Wnt signaling and inactivated Rb tumor suppressor.

  14. Rabconnectin-3a regulates vesicle endocytosis and canonical Wnt signaling in zebrafish neural crest migration.

    Directory of Open Access Journals (Sweden)

    Adam M Tuttle

    2014-05-01

    Full Text Available Cell migration requires dynamic regulation of cell-cell signaling and cell adhesion. Both of these processes involve endocytosis, lysosomal degradation, and recycling of ligand-receptor complexes and cell adhesion molecules from the plasma membrane. Neural crest (NC cells in vertebrates are highly migratory cells, which undergo an epithelial-mesenchymal transition (EMT to leave the neural epithelium and migrate throughout the body to give rise to many different derivatives. Here we show that the v-ATPase interacting protein, Rabconnectin-3a (Rbc3a, controls intracellular trafficking events and Wnt signaling during NC migration. In zebrafish embryos deficient in Rbc3a, or its associated v-ATPase subunit Atp6v0a1, many NC cells fail to migrate and misregulate expression of cadherins. Surprisingly, endosomes in Rbc3a- and Atp6v0a1-deficient NC cells remain immature but still acidify. Rbc3a loss-of-function initially downregulates several canonical Wnt targets involved in EMT, but later Frizzled-7 accumulates at NC cell membranes, and nuclear B-catenin levels increase. Presumably due to this later Wnt signaling increase, Rbc3a-deficient NC cells that fail to migrate become pigment progenitors. We propose that Rbc3a and Atp6v0a1 promote endosomal maturation to coordinate Wnt signaling and intracellular trafficking of Wnt receptors and cadherins required for NC migration and cell fate determination. Our results suggest that different v-ATPases and associated proteins may play cell-type-specific functions in intracellular trafficking in many contexts.

  15. Association of single nucleotide polymorphisms in Wnt signaling pathway genes with breast cancer in Saudi patients.

    Directory of Open Access Journals (Sweden)

    Mohammad Saud Alanazi

    Full Text Available Breast cancer is a complex heterogeneous disease involving genetic and epigenetic alterations in genes encoding proteins that are components of various signaling pathways. Candidate gene approach have identified association of genetic variants in the Wnt signaling pathway genes and increased susceptibility to several diseases including breast cancer. Due to the rarity of somatic mutations in key genes of Wnt pathway, we investigated the association of genetic variants in these genes with predisposition to breast cancers. We performed a case-control study to identify risk variants by examining 15 SNPs located in 8 genes associated with Wnt signaling. Genotypic analysis of individual locus showed statistically significant association of five SNPs located in β-catenin, AXIN2, DKK3, SFRP3 and TCF7L2 with breast cancers. Increased risk was observed only with the SNP in β-catenin while the other four SNPs conferred protection against breast cancers. Majority of these associations persisted after stratification of the cases based on estrogen receptor status and age of on-set of breast cancer. The rs7775 SNP in exon 6 of SFRP3 gene that codes for either arginine or glycine exhibited very strong association with breast cancer, even after Bonferroni's correction. Apart from these five variants, rs3923086 in AXIN2 and rs3763511 in DKK4 that did not show any association in the overall population were significantly associated with early on-set and estrogen receptor negative breast cancers, respectively. This is the first study to utilize pathway based approach to identify association of risk variants in the Wnt signaling pathway genes with breast cancers. Confirmation of our findings in larger populations of different ethnicities would provide evidence for the role of Wnt pathway as well as screening markers for early detection of breast carcinomas.

  16. WNT antagonist, DKK2, is a Notch signaling target in intestinal stem cells: augmentation of a negative regulation system for canonical WNT signaling pathway by the Notch-DKK2 signaling loop in primates.

    Science.gov (United States)

    Katoh, Masuko; Katoh, Masaru

    2007-01-01

    Notch and WNT signaling pathways are key components of the stem cell signaling network. Canonical WNT signaling to intestinal progenitor cells leads to transcriptional activation of the JAG1 gene, encoding Serrate-type Notch ligand. JAG1 then binds to the Notch receptor on adjacent stem cells to induce Notch receptor proteolyses for the release of Notch intracellular domain (NICD). NICD is associated with CSL/RBPSUH and Mastermind (MAML1, MAML2, or MAML3) to activate Notch target genes, such as HES1 and HES5. Although WNT-dependent Notch signaling activation in intestinal stem cells is clarified, the effects of Notch signaling activation on WNT signaling in progenitor cells remain unclear. We searched for Notch-response element (NRE) in the promoter region of genes encoding secreted WNT signaling inhibitors, including DKK1, DKK2, DKK3, DKK4, SFRP1, SFRP2, SFRP3, SFRP4, SFRP5 and WIF1. Double NREs were identified within human DKK2 promoter by bioinformatics and human intelligence (Humint). The human DKK2 gene was characterized as Notch signaling target in intestinal stem cells. Because DKK2 is a key player in the stem cell signaling network, the DKK2 gene at human chromosome 4q25 is a candidate tumor suppressor gene inactivated due to epigenetic silencing and/or deletion. The chimpanzee DKK2 gene was identified within the NW_105990.1 genome sequence, while the cow Dkk2 gene was identified within the AC156664.2 and AC158038.2 genome sequences. Chimpanzee DKK2 and cow Dkk2 showed 98.5% and 95.8% total-amino-acid identity with human DKK2, respectively. Double NREs in human DKK2 promoter were conserved in chimpanzee DKK2 promoter, partially in rat Dkk2 promoter, but not in cow and mouse Dkk2 promoters. The Notch-DKK2 signaling loop, created or potentiated in primates, was complementary to WNT-DKK1 and BMP-IHH-SFRP1 signaling loops for negative regulation of canonical WNT signaling pathway. Together, these facts indicate that DKK2 promoter evolution resulted in the

  17. Restoration of anatomical continuity after spinal cord transection depends on Wnt/β-catenin signaling in larval zebrafish

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    Daniel Wehner

    2018-02-01

    Full Text Available This data article contains descriptive and experimental data on spinal cord regeneration in larval zebrafish and its dependence on Wnt/β-catenin signaling. Analyzing spread of intraspinally injected fluorescent dextran showed that anatomical continuity is rapidly restored after complete spinal cord transection. Pharmacological interference with Wnt/β-catenin signaling (IWR-1 impaired restoration of spinal continuity. For further details and experimental findings please refer to the research article by Wehner et al. Wnt signaling controls pro-regenerative Collagen XII in functional spinal cord regeneration in zebrafish (Wehner et al., 2017 [1].

  18. Nucleotide variants of genes encoding components of the Wnt signalling pathway and the risk of non-syndromic tooth agenesis.

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    Mostowska, A; Biedziak, B; Zadurska, M; Dunin-Wilczynska, I; Lianeri, M; Jagodzinski, P P

    2013-11-01

    Tooth agenesis is one of the most common dental anomalies, with a complex and not yet fully elucidated aetiology. Given the crucial role of the Wnt signalling pathway during tooth development, the purpose of this study was to determine whether nucleotide variants of genes encoding components of this signalling pathway might be associated with hypodontia and oligodontia in the Polish population. A set of 34 single nucleotide polymorphism (SNPs) in 13 WNT and WNT-related genes were analyzed in a group of 157 patients with tooth agenesis and a properly matched control group (n = 430). In addition, direct sequencing was performed to detect mutations in the MSX1, PAX9 and WNT10A genes. Both single-marker and haplotype analyses showed highly significant association between SNPs in the WNT10A gene and the risk for tooth agenesis. Moreover, nine pathogenic mutations within the coding region of the WNT10A gene were identified in 26 out of 42 (62%) tested patients. One novel heterozygous mutation was identified in the PAX9 gene. Borderline association with the risk of non-syndromic tooth agenesis was also observed for the APC, CTNNB1, DVL2 and WNT11 polymorphisms. In conclusion, nucleotide variants of genes encoding important components of the Wnt signalling pathway might influence the risk of tooth agenesis. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Loss of FTO antagonises Wnt signaling and leads to developmental defects associated with ciliopathies.

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    Daniel P S Osborn

    Full Text Available Common intronic variants in the Human fat mass and obesity-associated gene (FTO are found to be associated with an increased risk of obesity. Overexpression of FTO correlates with increased food intake and obesity, whilst loss-of-function results in lethality and severe developmental defects. Despite intense scientific discussions around the role of FTO in energy metabolism, the function of FTO during development remains undefined. Here, we show that loss of Fto leads to developmental defects such as growth retardation, craniofacial dysmorphism and aberrant neural crest cells migration in Zebrafish. We find that the important developmental pathway, Wnt, is compromised in the absence of FTO, both in vivo (zebrafish and in vitro (Fto(-/- MEFs and HEK293T. Canonical Wnt signalling is down regulated by abrogated β-Catenin translocation to the nucleus whilst non-canonical Wnt/Ca(2+ pathway is activated via its key signal mediators CaMKII and PKCδ. Moreover, we demonstrate that loss of Fto results in short, absent or disorganised cilia leading to situs inversus, renal cystogenesis, neural crest cell defects and microcephaly in Zebrafish. Congruently, Fto knockout mice display aberrant tissue specific cilia. These data identify FTO as a protein-regulator of the balanced activation between canonical and non-canonical branches of the Wnt pathway. Furthermore, we present the first evidence that FTO plays a role in development and cilia formation/function.

  20. High Levels of Canonical Wnt Signaling Lead to Loss of Stemness and Increased Differentiation in Hematopoietic Stem Cells

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    Farbod Famili

    2016-05-01

    Full Text Available Canonical Wnt signaling regulates the self-renewal of most if not all stem cell systems. In the blood system, the role of Wnt signaling has been the subject of much debate but there is consensus that high Wnt signals lead to loss of reconstituting capacity. To better understand this phenomenon, we have taken advantage of a series of hypomorphic mutant Apc alleles resulting in a broad range of Wnt dosages in hematopoietic stem cells (HSCs and performed whole-genome gene expression analyses. Gene expression profiling and functional studies show that HSCs with APC mutations lead to high Wnt levels, enhanced differentiation, and diminished proliferation but have no effect on apoptosis, collectively leading to loss of stemness. Thus, we provide mechanistic insight into the role of APC mutations and Wnt signaling in HSC biology. As Wnt signals are explored in various in vivo and ex vivo expansion protocols for HSCs, our findings also have clinical ramifications.

  1. Loss of Pancreas upon Activated Wnt Signaling Is Concomitant with Emergence of Gastrointestinal Identity.

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    Muñoz-Bravo, Jose Luis; Flores-Martínez, Alvaro; Herrero-Martin, Griselda; Puri, Sapna; Taketo, Makoto Mark; Rojas, Anabel; Hebrok, Matthias; Cano, David A

    2016-01-01

    Organ formation is achieved through the complex interplay between signaling pathways and transcriptional cascades. The canonical Wnt signaling pathway plays multiple roles during embryonic development including patterning, proliferation and differentiation in distinct tissues. Previous studies have established the importance of this pathway at multiple stages of pancreas formation as well as in postnatal organ function and homeostasis. In mice, gain-of-function experiments have demonstrated that activation of the canonical Wnt pathway results in pancreatic hypoplasia, a phenomenon whose underlying mechanisms remains to be elucidated. Here, we show that ectopic activation of epithelial canonical Wnt signaling causes aberrant induction of gastric and intestinal markers both in the pancreatic epithelium and mesenchyme, leading to the development of gut-like features. Furthermore, we provide evidence that β -catenin-induced impairment of pancreas formation depends on Hedgehog signaling. Together, our data emphasize the developmental plasticity of pancreatic progenitors and further underscore the key role of precise regulation of signaling pathways to maintain appropriate organ boundaries.

  2. Expression of the Wnt signaling system in central nervous system axon guidance and regeneration

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    Edmund eHollis

    2012-02-01

    Full Text Available Wnt signaling is essential for axon wiring throughout the development of the nervous system in vertebrates and invertebrates. In vertebrates, Wnts are expressed in gradients that span the entire anterior-posterior axis in the spinal cord and the medial-lateral axis in the superior colliculus. In the brainstem, Wnts are expressed in more complex gradients along the anterior-posterior axis. These gradients provide directional information for axon pathfinding and positional information for topographic mapping and are detected by cell polarity signaling pathways. The gradient expression of Wnts and the coordinated expression of Wnt signaling systems are regulated by mechanisms which are currently unknown. Injury to the adult spinal cord results in the re-induction of Wnts in multiple cell types around the lesion site and their signaling system in injured axons. Reinduced Wnts form gradients around the lesion site, with the lesion site being the peak. The reinduced Wnts may be responsible for the well-known retraction of descending motor axons through the atypical kinase receptor Ryk. Wnt signaling is an appealing therapeutic target for CNS repair. The mechanisms regulating the reinduction will be informative for therapeutic design.

  3. Serotonin signaling is required for Wnt-dependent GRP specification and leftward flow in Xenopus.

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    Beyer, Tina; Danilchik, Michael; Thumberger, Thomas; Vick, Philipp; Tisler, Matthias; Schneider, Isabelle; Bogusch, Susanne; Andre, Philipp; Ulmer, Bärbel; Walentek, Peter; Niesler, Beate; Blum, Martin; Schweickert, Axel

    2012-01-10

    In vertebrates, most inner organs are asymmetrically arranged with respect to the main body axis [1]. Symmetry breakage in fish, amphibian, and mammalian embryos depends on cilia-driven leftward flow of extracellular fluid during neurulation [2-5]. Flow induces the asymmetric nodal cascade that governs asymmetric organ morphogenesis and placement [1, 6, 7]. In the frog Xenopus, an alternative laterality-generating mechanism involving asymmetric localization of serotonin at the 32-cell stage has been proposed [8]. However, no functional linkage between this early localization and flow at neurula stage has emerged. Here, we report that serotonin signaling is required for specification of the superficial mesoderm (SM), which gives rise to the ciliated gastrocoel roof plate (GRP) where flow occurs [5, 9]. Flow and asymmetry were lost in embryos in which serotonin signaling was downregulated. Serotonin, which we found uniformly distributed along the main body axes in the early embryo, was required for Wnt signaling, which provides the instructive signal to specify the GRP. Importantly, serotonin was required for Wnt-induced double-axis formation as well. Our data confirm flow as primary mechanism of symmetry breakage and suggest a general role of serotonin as competence factor for Wnt signaling during axis formation in Xenopus. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Loss of Pancreas upon Activated Wnt Signaling Is Concomitant with Emergence of Gastrointestinal Identity

    Science.gov (United States)

    Herrero-Martin, Griselda; Puri, Sapna; Taketo, Makoto Mark; Rojas, Anabel; Hebrok, Matthias; Cano, David A.

    2016-01-01

    Organ formation is achieved through the complex interplay between signaling pathways and transcriptional cascades. The canonical Wnt signaling pathway plays multiple roles during embryonic development including patterning, proliferation and differentiation in distinct tissues. Previous studies have established the importance of this pathway at multiple stages of pancreas formation as well as in postnatal organ function and homeostasis. In mice, gain-of-function experiments have demonstrated that activation of the canonical Wnt pathway results in pancreatic hypoplasia, a phenomenon whose underlying mechanisms remains to be elucidated. Here, we show that ectopic activation of epithelial canonical Wnt signaling causes aberrant induction of gastric and intestinal markers both in the pancreatic epithelium and mesenchyme, leading to the development of gut-like features. Furthermore, we provide evidence that β -catenin-induced impairment of pancreas formation depends on Hedgehog signaling. Together, our data emphasize the developmental plasticity of pancreatic progenitors and further underscore the key role of precise regulation of signaling pathways to maintain appropriate organ boundaries. PMID:27736991

  5. Activin and Bmp4 Signaling Converge on Wnt Activation during Odontogenesis.

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    Kwon, H-J E; Jia, S; Lan, Y; Liu, H; Jiang, R

    2017-09-01

    Previous studies show that both activin and Bmp4 act as crucial mesenchymal odontogenic signals during early tooth development. Remarkably, mice lacking activin-βA ( Inhba-/-) and mice with neural crest-specific inactivation of Bmp4 ( Bmp4ncko/ncko) both exhibit bud-stage developmental arrest of the mandibular molar tooth germs while their maxillary molar tooth germs completed morphogenesis. In this study, we found that, whereas expression of Inhba and Bmp4 in the developing tooth mesenchyme is independent of each other, Bmp4ncko/nckoInhba-/- compound mutant mice exhibit early developmental arrest of all tooth germs. Moreover, genetic inactivation of Osr2, a negative regulator of the odontogenic function of the Bmp4-Msx1 signaling pathway, rescues mandibular molar morphogenesis in Inhba-/- embryos. We recently reported that Osr2 and the Bmp4-Msx1 pathway control the bud-to-cap transition of tooth morphogenesis through antagonistic regulation of expression of secreted Wnt antagonists, including Dkk2 and Sfrp2, in the developing tooth mesenchyme. We show here that expression of Dkk2 messenger RNAs was significantly upregulated and expanded into the tooth bud mesenchyme in Inhba-/- embryos in comparison with wild-type littermates. Furthermore, in utero treatment with either lithium chloride, an agonist of canonical Wnt signaling, or the DKK inhibitor IIIC3a rescued mandibular molar tooth morphogenesis in Inhba-/- embryos. Together with our finding that the developing mandibular molar tooth bud mesenchyme expresses significantly higher levels of Dkk2 than the developing maxillary molar tooth mesenchyme, these data indicate that Bmp4 and activin signaling pathways converge on activation of the Wnt signaling pathway to promote tooth morphogenesis through the bud-to-cap transition and that the differential effects of loss of activin or Bmp4 signaling on maxillary and mandibular molar tooth morphogenesis are mainly due to the differential expression of Wnt antagonists

  6. Canonical Wnt signaling promotes early hematopoietic progenitor formation and erythroid specification during embryonic stem cell differentiation.

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    Tarafdar, Anuradha; Dobbin, Edwina; Corrigan, Pamela; Freeburn, Robin; Wheadon, Helen

    2013-01-01

    The generation of hematopoietic stem cells (HSCs) during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/β-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between β-catenin/TCF/LEF/Brachyury/Nanog. β-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. β-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP) formation. Following culture in a MPP specific cytokine cocktail, activation of β-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/β-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.

  7. Canonical Wnt signaling promotes early hematopoietic progenitor formation and erythroid specification during embryonic stem cell differentiation.

    Directory of Open Access Journals (Sweden)

    Anuradha Tarafdar

    Full Text Available The generation of hematopoietic stem cells (HSCs during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/β-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between β-catenin/TCF/LEF/Brachyury/Nanog. β-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. β-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP formation. Following culture in a MPP specific cytokine cocktail, activation of β-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/β-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.

  8. Wnt signalling requires MTM-6 and MTM-9 myotubularin lipid-phosphatase function in Wnt-producing cells.

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    Silhankova, Marie; Port, Fillip; Harterink, Martin; Basler, Konrad; Korswagen, Hendrik C

    2010-12-15

    Wnt proteins are lipid-modified glycoproteins that have important roles in development, adult tissue homeostasis and disease. Secretion of Wnt proteins from producing cells is mediated by the Wnt-binding protein MIG-14/Wls, which binds Wnt in the Golgi network and transports it to the cell surface for release. It has recently been shown that recycling of MIG-14/Wls from the plasma membrane to the trans-Golgi network is required for efficient Wnt secretion, but the mechanism of this retrograde transport pathway is still poorly understood. In this study, we report the identification of MTM-6 and MTM-9 as novel regulators of MIG-14/Wls trafficking in Caenorhabditis elegans. MTM-6 and MTM-9 are myotubularin lipid phosphatases that function as a complex to dephosphorylate phosphatidylinositol-3-phosphate, a central regulator of endosomal trafficking. We show that mutation of mtm-6 or mtm-9 leads to defects in several Wnt-dependent processes and demonstrate that MTM-6 is required in Wnt-producing cells as part of the MIG-14/Wls-recycling pathway. This function is evolutionarily conserved, as the MTM-6 orthologue DMtm6 is required for Wls stability and Wg secretion in Drosophila. We conclude that regulation of endosomal trafficking by the MTM-6/MTM-9 myotubularin complex is required for the retromer-dependent recycling of MIG-14/Wls and Wnt secretion.

  9. A Cascade of Wnt, Eda, and Shh Signaling Is Essential for Touch Dome Merkel Cell Development.

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    Ying Xiao

    2016-07-01

    Full Text Available The Sonic hedgehog (Shh signaling pathway regulates developmental, homeostatic, and repair processes throughout the body. In the skin, touch domes develop in tandem with primary hair follicles and contain sensory Merkel cells. The developmental signaling requirements for touch dome specification are largely unknown. We found dermal Wnt signaling and subsequent epidermal Eda/Edar signaling promoted Merkel cell morphogenesis by inducing Shh expression in early follicles. Lineage-specific gene deletions revealed intraepithelial Shh signaling was necessary for Merkel cell specification. Additionally, a Shh signaling agonist was sufficient to rescue Merkel cell differentiation in Edar-deficient skin. Moreover, Merkel cells formed in Fgf20 mutant skin where primary hair formation was defective but Shh production was preserved. Although developmentally associated with hair follicles, fate mapping demonstrated Merkel cells primarily originated outside the hair follicle lineage. These findings suggest that touch dome development requires Wnt-dependent mesenchymal signals to establish reciprocal signaling within the developing ectoderm, including Eda signaling to primary hair placodes and ultimately Shh signaling from primary follicles to extrafollicular Merkel cell progenitors. Shh signaling often demonstrates pleiotropic effects within a structure over time. In postnatal skin, Shh is known to regulate the self-renewal, but not the differentiation, of touch dome stem cells. Our findings relate the varied effects of Shh in the touch dome to the ligand source, with locally produced Shh acting as a morphogen essential for lineage specification during development and neural Shh regulating postnatal touch dome stem cell maintenance.

  10. Quantitative and kinetic profile of Wnt/β-catenin signaling components during human neural progenitor cell differentiation.

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    Mazemondet, Orianne; Hubner, Rayk; Frahm, Jana; Koczan, Dirk; Bader, Benjamin M; Weiss, Dieter G; Uhrmacher, Adelinde M; Frech, Moritz J; Rolfs, Arndt; Luo, Jiankai

    2011-12-01

    ReNcell VM is an immortalized human neural progenitor cell line with the ability to differentiate in vitro into astrocytes and neurons, in which the Wnt/β-catenin pathway is known to be involved. However, little is known about kinetic changes of this pathway in human neural progenitor cell differentiation. In the present study, we provide a quantitative profile of Wnt/β-catenin pathway dynamics showing its spatio-temporal regulation during ReNcell VM cell differentiation. We show first that T-cell factor dependent transcription can be activated by stabilized β-catenin. Furthermore, endogenous Wnt ligands, pathway receptors and signaling molecules are temporally controlled, demonstrating changes related to differentiation stages. During the first three hours of differentiation the signaling molecules LRP6, Dvl2 and β-catenin are spatio-temporally regulated between distinct cellular compartments. From 24 h onward, components of the Wnt/β-catenin pathway are strongly activated and regulated as shown by mRNA up-regulation of Wnt ligands (Wnt5a and Wnt7a), receptors including Frizzled-2, -3, -6, -7, and -9, and co-receptors, and target genes including Axin2. This detailed temporal profile of the Wnt/β-catenin pathway is a first step to understand, control and to orientate, in vitro, human neural progenitor cell differentiation.

  11. The role of Wnt/β-catenin signaling in proliferation and regeneration of the developing basilar papilla and lateral line.

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    Jacques, Bonnie E; Montgomery, William H; Uribe, Phillip M; Yatteau, Andrew; Asuncion, James D; Resendiz, Genesis; Matsui, Jonathan I; Dabdoub, Alain

    2014-04-01

    Canonical Wnt/β-catenin signaling has been implicated in multiple developmental events including the regulation of proliferation, cell fate, and differentiation. In the inner ear, Wnt/β-catenin signaling is required from the earliest stages of otic placode specification through the formation of the mature cochlea. Within the avian inner ear, the basilar papilla (BP), many Wnt pathway components are expressed throughout development. Here, using reporter constructs for Wnt/β-catenin signaling, we show that this pathway is active throughout the BP (E6-E14) in both hair cells (HCs) and supporting cells. To characterize the role of Wnt/β-catenin activity in developing HCs, we performed gain- and loss-of-function experiments in vitro and in vivo in the chick BP and zebrafish lateral line systems, respectively. Pharmacological inhibition of Wnt signaling in the BP and lateral line neuromasts during the periods of proliferation and HC differentiation resulted in reduced proliferation and decreased HC formation. Conversely, pharmacological activation of this pathway significantly increased the number of HCs in the lateral line and BP. Results demonstrated that this increase was the result of up-regulated cell proliferation within the Sox2-positive cells of the prosensory domains. Furthermore, Wnt/β-catenin activation resulted in enhanced HC regeneration in the zebrafish lateral line following aminoglycoside-induced HC loss. Combined, our data suggest that Wnt/β-catenin signaling specifies the number of cells within the prosensory domain and subsequently the number of HCs. This ability to induce proliferation suggests that the modulation of Wnt/β-catenin signaling could play an important role in therapeutic HC regeneration. Copyright © 2013 Wiley Periodicals, Inc.

  12. Canonical Wnt signaling promotes the proliferation and neurogenesis of peripheral olfactory stem cells during postnatal development and adult regeneration.

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    Wang, Ya-Zhou; Yamagami, Takashi; Gan, Qini; Wang, Yongping; Zhao, Tianyu; Hamad, Salaheddin; Lott, Paul; Schnittke, Nikolai; Schwob, James E; Zhou, Chengji J

    2011-05-01

    The mammalian olfactory epithelium (OE) has a unique stem cell or progenitor niche, which is responsible for the constant peripheral neurogenesis throughout the lifespan of the animal. However, neither the signals that regulate the behavior of these cells nor the lineage properties of the OE stem cells are well understood. Multiple Wnt signaling components exhibit dynamic expression patterns in the developing OE. We generated Wnt signaling reporter TOPeGFP transgenic mice and found TOPeGFP activation predominantly in proliferating Sox2(+) OE basal cells during early postnatal development. FACS-isolated TOPeGFP(+) OE basal cells are required, but are not sufficient, for formation of spheres. Wnt3a significantly promotes the proliferation of the Sox2(+) OE sphere cells. Wnt-stimulated OE sphere cells maintain their multipotency and can differentiate into most types of neuronal and non-neuronal epithelial cells. Also, Wnt activators shift the production of differentiated cells toward olfactory sensory neurons. Moreover, TOPeGFP(+) cells are robustly increased in the adult OE after injury. In vivo administration of Wnt modulators significantly alters the regeneration potential. This study demonstrates the role of the canonical Wnt signaling pathway in the regulation of OE stem cells or progenitors during development and regeneration.

  13. Temporal Perturbation of the Wnt Signaling Pathway in the Control of Cell Reprogramming Is Modulated by TCF1

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    Francesco Aulicino

    2014-05-01

    Full Text Available Cyclic activation of the Wnt/β-catenin signaling pathway controls cell fusion-mediated somatic cell reprogramming. TCFs belong to a family of transcription factors that, in complex with β-catenin, bind and transcriptionally regulate Wnt target genes. Here, we show that Wnt/β-catenin signaling needs to be off during the early reprogramming phases of mouse embryonic fibroblasts (MEFs into iPSCs. In MEFs undergoing reprogramming, senescence genes are repressed and mesenchymal-to-epithelial transition is favored. This is correlated with a repressive activity of TCF1, which contributes to the silencing of Wnt/β-catenin signaling at the onset of reprogramming. In contrast, the Wnt pathway needs to be active in the late reprogramming phases to achieve successful reprogramming. In conclusion, continued activation or inhibition of the Wnt/β-catenin signaling pathway is detrimental to the reprogramming of MEFs; instead, temporal perturbation of the pathway is essential for efficient reprogramming, and the “Wnt-off” state can be considered an early reprogramming marker.

  14. Apical constriction and invagination downstream of the canonical Wnt signaling pathway require Rho1 and Myosin II.

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    Zimmerman, Sandra G; Thorpe, Lauren M; Medrano, Vilma R; Mallozzi, Carolyn A; McCartney, Brooke M

    2010-04-01

    The tumor suppressor Adenomatous polyposis coli (APC) is a negative regulator of Wnt signaling and functions in cytoskeletal organization. Disruption of human APC in colonic epithelia initiates benign polyps that progress to carcinoma following additional mutations. The early events of polyposis are poorly understood, as is the role of canonical Wnt signaling in normal epithelial architecture and morphogenesis. To determine the consequences of complete loss of APC in a model epithelium, we generated APC2 APC1 double null clones in the Drosophila wing imaginal disc. APC loss leads to segregation, apical constriction, and invagination that result from transcriptional activation of canonical Wnt signaling. Further, we show that Wnt-dependent changes in cell fate can be decoupled from Wnt-dependent changes in cell shape. Wnt activation is reported to upregulate DE-cadherin in wing discs, and elevated DE-cadherin is thought to promote apical constriction. We find that apical constriction and invagination of APC null tissue are independent of DE-cadherin elevation, but are dependent on Myosin II activity. Further, we show that disruption of Rho1 suppresses apical constriction and invagination in APC null cells. Our data suggest a novel link between canonical Wnt signaling and epithelial structure that requires activation of the Rho1 pathway and Myosin II. Copyright 2010 Elsevier Inc. All rights reserved.

  15. Apical constriction and invagination downstream of the canonical Wnt signaling pathway requires Rho1 and Myosin II

    Science.gov (United States)

    Zimmerman, Sandra G.; Thorpe, Lauren M.; Medrano, Vilma R.; Mallozzi, Carolyn A.; McCartney, Brooke M.

    2010-01-01

    The tumor suppressor Adenomatous polyposis coli (APC) is a negative regulator of Wnt signaling and functions in cytoskeletal organization. Disruption of human APC in colonic epithelia initiates benign polyps that progress to carcinoma following additional mutations. The early events of polyposis are poorly understood, as is the role of canonical Wnt signaling in normal epithelial architecture and morphogenesis. To determine the consequences of complete loss of APC in a model epithelium, we generated APC2 APC1 double null clones in the Drosophila wing imaginal disc. APC loss leads to segregation, apical constriction, and invagination that result from transcriptional activation of canonical Wnt signaling. Further, we show that Wnt-dependent changes in cell fate can be decoupled from Wnt-dependent changes in cell shape. Wnt activation is reported to upregulate DE-cadherin in wing discs, and elevated DE-cadherin is thought to promote apical constriction. We find that apical constriction and invagination of APC null tissue are independent of DE-cadherin elevation, but are dependent on Myosin II activity. Further, we show that disruption of Rho1 suppresses apical constriction and invagination in APC null cells. Our data suggest a novel link between canonical Wnt signaling and epithelial structure that requires activation of the Rho1 pathway and Myosin II. PMID:20102708

  16. Wnt and BMP Signaling Crosstalk in Regulating Dental Stem Cells: Implications in Dental Tissue Engineering.

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    Zhang, Fugui; Song, Jinglin; Zhang, Hongmei; Huang, Enyi; Song, Dongzhe; Tollemar, Viktor; Wang, Jing; Wang, Jinhua; Mohammed, Maryam; Wei, Qiang; Fan, Jiaming; Liao, Junyi; Zou, Yulong; Liu, Feng; Hu, Xue; Qu, Xiangyang; Chen, Liqun; Yu, Xinyi; Luu, Hue H; Lee, Michael J; He, Tong-Chuan; Ji, Ping

    2016-12-01

    Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling. Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance, essential oral functions and the quality of life. Regenerative dentistry holds great promise in treating oral/dental disorders. The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells, along with the signaling mechanisms governing stem cell self-renewal and differentiation. In this review, we first summarize the biological characteristics of seven types of dental stem cells, including dental pulp stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, periodontal ligament stem cells, alveolar bone-derived mesenchymal stem cells (MSCs), and MSCs from gingiva. We then focus on how these stem cells are regulated by bone morphogenetic protein (BMP) and/or Wnt signaling by examining the interplays between these pathways. Lastly, we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways. We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications. Thus, we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.

  17. Wnt and BMP signaling crosstalk in regulating dental stem cells: Implications in dental tissue engineering

    Directory of Open Access Journals (Sweden)

    Fugui Zhang

    2016-12-01

    Full Text Available Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling. Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance, essential oral functions and the quality of life. Regenerative dentistry holds great promise in treating oral/dental disorders. The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells, along with the signaling mechanisms governing stem cell self-renewal and differentiation. In this review, we first summarize the biological characteristics of seven types of dental stem cells, including dental pulp stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, periodontal ligament stem cells, alveolar bone-derived mesenchymal stem cells (MSCs, and MSCs from gingiva. We then focus on how these stem cells are regulated by bone morphogenetic protein (BMP and/or Wnt signaling by examining the interplays between these pathways. Lastly, we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways. We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications. Thus, we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.

  18. Altered Wnt signalling in the teenage suicide brain: focus on glycogen synthase kinase-3β and β-catenin

    National Research Council Canada - National Science Library

    Ren, Xinguo; Rizavi, Hooriyah S; Khan, Mansoor A; Dwivedi, Yogesh; Pandey, Ghanshyam N

    2013-01-01

    Glycogen synthase kinase (GSK)-3β and β-catenin are important components of the Wnt signalling pathway, which is involved in numerous physiological functions such as cognition, brain development and cell survival...

  19. Altered Wnt signalling in the teenage suicide brain: focus on glycogen synthase kinase-3[beta] and [beta]-catenin

    National Research Council Canada - National Science Library

    Xinguo Ren; Hooriyah S Rizavi; Mansoor A Khan; Yogesh Dwivedi; Ghanshyam N Pandey

    2013-01-01

      Abstract Glycogen synthase kinase (GSK)-3[beta] and [beta]-catenin are important components of the Wnt signalling pathway, which is involved in numerous physiological functions such as cognition, brain development and cell survival...

  20. Pentoxifylline Inhibits WNT Signalling in β-Cateninhigh Patient-Derived Melanoma Cell Populations.

    Directory of Open Access Journals (Sweden)

    Beata Talar

    Full Text Available The heterogeneity of melanoma needs to be addressed and combination therapies seem to be necessary to overcome intrinsic and acquired resistance to newly developed immunotherapies and targeted therapies. Although the role of WNT/β-catenin pathway in melanoma was early demonstrated, its contribution to the lack of the melanoma patient response to treatment was only recently recognized. Using patient-derived melanoma cell populations, we investigated the influence of pentoxifylline on melanoma cells with either high or low expression of β-catenin.Our results indicate that pentoxifylline inhibits the activity of the canonical WNT pathway in melanoma cell populations with high basal activity of this signalling. This is supported by lowered overall activity of transcription factors TCF/LEF and reduced nuclear localisation of active β-catenin. Moreover, treatment of β-cateninhigh melanoma cell populations with pentoxifylline induces downregulation of genes that are targets of the WNT/β-catenin pathway including connective tissue growth factor (CTGF and microphthalmia-associated transcription factor (MITF-M, a melanocyte- and melanoma cell-specific regulator.These results suggest that pentoxifylline, a drug approved by the FDA in the treatment of peripheral arterial disease, might be tested in a subset of melanoma patients with elevated activity of β-catenin. This pharmaceutical might be tested as an adjuvant drug in combination therapies when the response to immunotherapy is prevented by high activity of the WNT/β-catenin pathway.

  1. An autocrine Wnt5a-Ror signaling loop mediates sympathetic target innervation.

    Science.gov (United States)

    Ryu, Yun Kyoung; Collins, Sarah Ellen; Ho, Hsin-Yi Henry; Zhao, Haiqing; Kuruvilla, Rejji

    2013-05-01

    During nervous system development, axon branching at nerve terminals is an essential step in the formation of functional connections between neurons and target cells. It is known that target tissues exert control of terminal arborization through secretion of trophic factors. However, whether the in-growing axons themselves produce diffusible cues to instruct target innervation remains unclear. Here, we use conditional mutant mice to show that Wnt5a derived from sympathetic neurons is required for their target innervation in vivo. Conditional deletion of Wnt5a resulted in specific deficits in the extension and arborization of sympathetic fibers in their final target fields, while no defects were observed in the overall tissue patterning, proliferation, migration or differentiation of neuronal progenitors. Using compartmentalized neuronal cultures, we further demonstrate that the Ror receptor tyrosine kinases are required locally in sympathetic axons to mediate Wnt5a-dependent branching. Thus, our study suggests an autocrine Wnt5a-Ror signaling pathway that directs sympathetic axon branching during target innervation. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Thymosin β4 Prevents Angiotensin II-Induced Cardiomyocyte Growth by Regulating Wnt/WISP Signaling.

    Science.gov (United States)

    Li, Li; Guleria, Rakeshwar S; Thakur, Suresh; Zhang, Cheng-Lin; Pan, Jing; Baker, Kenneth M; Gupta, Sudhiranjan

    2016-08-01

    Thymosin beta-4 (Tβ4) is a ubiquitous protein with many properties relating to cell proliferation and differentiation that promotes wound healing and modulates inflammatory mediators. However, the role of Tβ4 in cardiomyocyte hypertrophy is currently unknown. The purpose of this study was to determine the cardio-protective effect of Tβ4 in angiotensin II (Ang II)-induced cardiomyocyte growth. Neonatal rat ventricular cardiomyocytes (NRVM) were pretreated with Tβ4 followed by Ang II stimulation. Cell size, hypertrophy marker gene expression and Wnt signaling components, β-catenin, and Wnt-induced secreted protein-1 (WISP-1) were evaluated by quantitative real-time PCR, Western blotting and fluorescent microscopy. Pre-treatment of Tβ4 resulted in reduction of cell size, hypertrophy marker genes and Wnt-associated gene expression, and protein levels; induced by Ang II in cardiomyocyte. WISP-1 was overexpressed in NRVM and, the effect of Tβ4 in Ang II-induced cardiomyocyte growth was evaluated. WISP-1 overexpression promoted cardiomyocytes growth and was reversed by pretreatment with Tβ4. This is the first report which demonstrates that Tβ4 targets Wnt/WISP-1 to protect Ang II-induced cardiomyocyte growth. J. Cell. Physiol. 231: 1737-1744, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  3. Prostate Cancer Stem Cells and Nanotechnology: A Focus on Wnt Signaling.

    Science.gov (United States)

    Qin, Wei; Zheng, Yongjiang; Qian, Bin-Zhi; Zhao, Meng

    2017-01-01

    Prostate cancer is the most common cancer among men worldwide. However, current treatments for prostate cancer patients in advanced stage often fail because of relapse. Prostate cancer stem cells (PCSCs) are resistant to most standard therapies, and are considered to be a major mechanism of cancer metastasis and recurrence. In this review, we summarized current understanding of PCSCs and their self-renewal signaling pathways with a specific focus on Wnt signaling. Although multiple Wnt inhibitors have been developed to target PCSCs, their application is still limited by inefficient delivery and toxicity in vivo. Recently, nanotechnology has opened a new avenue for cancer drug delivery, which significantly increases specificity and reduces toxicity. These nanotechnology-based drug delivery methods showed great potential in targeting PCSCs. Here, we summarized current advancement of nanotechnology-based therapeutic strategies for targeting PCSCs and highlighted the challenges and perspectives in designing future therapies to eliminate PCSCs.

  4. ALFY-Controlled DVL3 Autophagy Regulates Wnt Signaling, Determining Human Brain Size.

    Science.gov (United States)

    Kadir, Rotem; Harel, Tamar; Markus, Barak; Perez, Yonatan; Bakhrat, Anna; Cohen, Idan; Volodarsky, Michael; Feintsein-Linial, Miora; Chervinski, Elana; Zlotogora, Joel; Sivan, Sara; Birnbaum, Ramon Y; Abdu, Uri; Shalev, Stavit; Birk, Ohad S

    2016-03-01

    Primary microcephaly is a congenital neurodevelopmental disorder of reduced head circumference and brain volume, with fewer neurons in the cortex of the developing brain due to premature transition between symmetrical and asymmetrical cellular division of the neuronal stem cell layer during neurogenesis. We now show through linkage analysis and whole exome sequencing, that a dominant mutation in ALFY, encoding an autophagy scaffold protein, causes human primary microcephaly. We demonstrate the dominant effect of the mutation in drosophila: transgenic flies harboring the human mutant allele display small brain volume, recapitulating the disease phenotype. Moreover, eye-specific expression of human mutant ALFY causes rough eye phenotype. In molecular terms, we demonstrate that normally ALFY attenuates the canonical Wnt signaling pathway via autophagy-dependent removal specifically of aggregates of DVL3 and not of Dvl1 or Dvl2. Thus, autophagic attenuation of Wnt signaling through removal of Dvl3 aggregates by ALFY acts in determining human brain size.

  5. ALFY-Controlled DVL3 Autophagy Regulates Wnt Signaling, Determining Human Brain Size.

    Directory of Open Access Journals (Sweden)

    Rotem Kadir

    2016-03-01

    Full Text Available Primary microcephaly is a congenital neurodevelopmental disorder of reduced head circumference and brain volume, with fewer neurons in the cortex of the developing brain due to premature transition between symmetrical and asymmetrical cellular division of the neuronal stem cell layer during neurogenesis. We now show through linkage analysis and whole exome sequencing, that a dominant mutation in ALFY, encoding an autophagy scaffold protein, causes human primary microcephaly. We demonstrate the dominant effect of the mutation in drosophila: transgenic flies harboring the human mutant allele display small brain volume, recapitulating the disease phenotype. Moreover, eye-specific expression of human mutant ALFY causes rough eye phenotype. In molecular terms, we demonstrate that normally ALFY attenuates the canonical Wnt signaling pathway via autophagy-dependent removal specifically of aggregates of DVL3 and not of Dvl1 or Dvl2. Thus, autophagic attenuation of Wnt signaling through removal of Dvl3 aggregates by ALFY acts in determining human brain size.

  6. Telomere protection and TRF2 expression are enhanced by the canonical Wnt signalling pathway.

    Science.gov (United States)

    Diala, Irmina; Wagner, Nicole; Magdinier, Frédérique; Shkreli, Marina; Sirakov, Maria; Bauwens, Serge; Schluth-Bolard, Caroline; Simonet, Thomas; Renault, Valérie M; Ye, Jing; Djerbi, Abdelnnadir; Pineau, Pascal; Choi, Jinkuk; Artandi, Steven; Dejean, Anne; Plateroti, Michelina; Gilson, Eric

    2013-04-01

    The DNA-binding protein TRF2 is essential for telomere protection and chromosome stability in mammals. We show here that TRF2 expression is activated by the Wnt/β-catenin signalling pathway in human cancer and normal cells as well as in mouse intestinal tissues. Furthermore, β-catenin binds to TRF2 gene regulatory regions that are functional in a luciferase transactivating assay. Reduced β-catenin expression in cancer cells triggers a marked increase in telomere dysfunction, which can be reversed by TRF2 overexpression. We conclude that the Wnt/β-catenin signalling pathway maintains a level of TRF2 critical for telomere protection. This is expected to have an important role during development, adult stem cell function and oncogenesis.

  7. Cranial Nerve Development Requires Co-Ordinated Shh and Canonical Wnt Signaling

    Science.gov (United States)

    Kurosaka, Hiroshi; Trainor, Paul A.; Leroux-Berger, Margot; Iulianella, Angelo

    2015-01-01

    Cranial nerves govern sensory and motor information exchange between the brain and tissues of the head and neck. The cranial nerves are derived from two specialized populations of cells, cranial neural crest cells and ectodermal placode cells. Defects in either cell type can result in cranial nerve developmental defects. Although several signaling pathways are known to regulate cranial nerve formation our understanding of how intercellular signaling between neural crest cells and placode cells is coordinated during cranial ganglia morphogenesis is poorly understood. Sonic Hedgehog (Shh) signaling is one key pathway that regulates multiple aspects of craniofacial development, but whether it co-ordinates cranial neural crest cell and placodal cell interactions during cranial ganglia formation remains unclear. In this study we examined a new Patched1 (Ptch1) loss-of-function mouse mutant and characterized the role of Ptch1 in regulating Shh signaling during cranial ganglia development. Ptch1Wig/ Wig mutants exhibit elevated Shh signaling in concert with disorganization of the trigeminal and facial nerves. Importantly, we discovered that enhanced Shh signaling suppressed canonical Wnt signaling in the cranial nerve region. This critically affected the survival and migration of cranial neural crest cells and the development of placodal cells as well as the integration between neural crest and placodes. Collectively, our findings highlight a novel and critical role for Shh signaling in cranial nerve development via the cross regulation of canonical Wnt signaling. PMID:25799573

  8. NKD1 marks intestinal and liver tumors linked to aberrant Wnt signaling

    Czech Academy of Sciences Publication Activity Database

    Stančíková, Jitka; Krausová, Michaela; Kolář, Michal; Fafílek, Bohumil; Švec, Jiří; Sedláček, Radislav; Neroldová, M.; Dobeš, Jan; Horázná, Monika; Janečková, Lucie; Vojtěchová, Martina; Oliverius, M.; Jirsa, M.; Kořínek, Vladimír

    2015-01-01

    Roč. 27, č. 2 (2015), s. 245-256 ISSN 1873-3913 R&D Projects: GA ČR GAP305/11/1780; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) LM2011032 Institutional support: RVO:68378050 Keywords : Wnt signaling * NKD 1 * Intestine * Liver * Colorectal cancer * Hepatocellular carcinoma Subject RIV: EB - Genetics ; Molecular Biology

  9. Curcumin reduces lung inflammation via Wnt/β-catenin signaling in mouse model of asthma.

    Science.gov (United States)

    Yang, Xia; Lv, Jian-Ning; Li, Hui; Jiao, Bo; Zhang, Qiu-Hong; Zhang, Yong; Zhang, Jie; Liu, Yan-Qin; Zhang, Ming; Shan, Hu; Zhang, Jin-Zhao; Wu, Run-Miao; Li, Ya-Li

    2017-05-01

    Asthma is a chronic inflammatory, heterogeneous airway disease affecting millions of people around the world. Curcumin has been found to have anti-inflammatory and antifibrosis effects. Researchers reported that curcumin regulated Wnt/β-catenin signaling in lots of cells. However, whether curcumin regulates the levels of Wnt/β-Catenin signaling in lung tissues and DCs (dendritic cells) remains unclear. In this study, we assessed the effects of curcumin on DCs and asthma. C57BL/6 mice immunized with OVA (ovalbumin) were challenged thrice with an aerosol of OVA every second day for 8 days. Dexamethasone or curcumin was administered intraperitoneally to OVA-immunized C57BL/6 mice on day 24 once a day for 9 days. Mice were analyzed for effects of curcumin on asthma, inflammatory cell infiltration and cytokine levels in lung tissue. DCs were isolated from mouse bone morrow. The surface markers CD40, CD86 and CD11c of DCs was detected by FACS (fluorescence activated cell sorting) and the function of DCs was detected by mixed lymphocyte reaction. The expression of GSK-3β and β-catenin was detected by Western Blot. Results showed that OVA increased the number of inflammatory factors in BALF (bronchoalveolar lavage fluid), elevated lung inflammation scores in mice. Curcumin dose-dependently reversed the alterations induced by OVA in the asthmatic mice. Curcumin activated Wnt/β-catenin signaling pathway in DCs and asthmatic mouse lungs. Curcumin could influence the morphology and function of DCs, ease asthma symptom and inflammatory reaction through the activation of Wnt/β-catenin signaling. These results provide new evidence new evidence for application of curcumin on asthma.

  10. Effects of Fruit Ellagitannin Extracts, Ellagic Acid, and Their Colonic Metabolite, Urolithin A, on Wnt Signaling

    Science.gov (United States)

    Sharma, Meenakshi; Li, Liya; Celver, Jeremy; Killian, Caroline; Kovoor, Abraham; Seeram, Navindra P.

    2010-01-01

    Recent data suggest that ellagitannins (ETs), a class of hydrolyzable tannins found in some fruits and nuts, may have beneficial effects against colon cancer. In the stomach and gut, ETs hydrolyze to release ellagic acid (EA) and are converted by gut microbiota to urolithin-A (UA; 3,8-dihydroxy-6H-dibenzopyran-6-one) type metabolites which may persist in the colon through enterohepatic circulation. However, little is known about the mechanisms of action of either the native compounds or their metabolites on colon carcinogenesis. Components of Wnt signaling pathways are known to play a pivotal role in human colon carcinogenesis and inappropriate activation of the signaling cascade is observed in 90% of colorectal cancers. Here we investigated the effects of UA, EA, and ET rich fruit extracts on Wnt signaling in a human 293T cell line using a luciferase reporter of canonical Wnt pathway-mediated transcriptional activation. The ET extracts were obtained from strawberry (Fragaria annassa), Jamun berry (Eugenia jambolana), and pomegranate (Punica granatum) fruit and were all standardized to phenolic content (as gallic acid equivalents, GAEs, by the Folin Ciocalteau method) and to EA content (by high performance liquid chromatography methods): strawberry=20.5% GAE, 5.0% EA; Jamun berry= 20.5% GAE, 4.2% EA; pomegranate= 55% GAE, 3.5% EA. The ET-extracts (IC50=28.0-30.0 μg/mL), EA (IC50=19.0 μg/mL; 63 μM) and UA (IC50=9.0 μg/mL; 39 μM) inhibited Wnt signaling suggesting that ET-rich foods have potential against colon carcinogenesis and that urolithins are relevant bioactive constituents in the colon. PMID:20014760

  11. Zebrafish foxo3b negatively regulates canonical Wnt signaling to affect early embryogenesis.

    Directory of Open Access Journals (Sweden)

    Xun-wei Xie

    Full Text Available FOXO genes are involved in many aspects of development and vascular homeostasis by regulating cell apoptosis, proliferation, and the control of oxidative stress. In addition, FOXO genes have been showed to inhibit Wnt/β-catenin signaling by competing with T cell factor to bind to β-catenin. However, how important of this inhibition in vivo, particularly in embryogenesis is still unknown. To demonstrate the roles of FOXO genes in embryogenesis will help us to further understand their relevant physiological functions. Zebrafish foxo3b gene, an orthologue of mammalian FOXO3, was expressed maternally and distributed ubiquitously during early embryogenesis and later restricted to brain. After morpholino-mediated knockdown of foxo3b, the zebrafish embryos exhibited defects in axis and neuroectoderm formation, suggesting its critical role in early embryogenesis. The embryo-developmental marker gene staining at different stages, phenotype analysis and rescue assays revealed that foxo3b acted its role through negatively regulating both maternal and zygotic Wnt/β-catenin signaling. Moreover, we found that foxo3b could interact with zebrafish β-catenin1 and β-catenin2 to suppress their transactivation in vitro and in vivo, further confirming its role relevant to the inhibition of Wnt/β-catenin signaling. Taken together, we revealed that foxo3b played a very important role in embryogenesis and negatively regulated maternal and zygotic Wnt/β-catenin signaling by directly interacting with both β-catenin1 and β-catenin2. Our studies provide an in vivo model for illustrating function of FOXO transcription factors in embryogenesis.

  12. Astragaloside IV Inhibits the Up-Regulation of Wnt/β-Catenin Signaling in Rats with Unilateral Ureteral Obstruction

    Directory of Open Access Journals (Sweden)

    Li Wang

    2014-04-01

    Full Text Available Objective: To investigate the effect of Astragaloside IV (AS-IV on the regulation of the Wnt/β-catenin signaling pathway in rats with unilateral ureteral obstruction (UUO. Methods: Rat renal interstitial fibrosis models were prepared using unilateral ureteral ligation. Rats were randomly divided into sham group, sham group with AS-IV (33mg/kg, unilateral ureteral obstruction group, and unilateral ureteral obstruction group receiving varied doses of AS-IV (3.3, 10, and 33 mg/kg. Immunohistochemical analysis, real-time fluorescence quantitative PCR (FQ-PCR, and western blot were used to detect the expression of genes and proteins associated with the Wnt/β-catenin signaling pathway in renal tissues. Results: Levels of Wnt3, Wnt4, and Frizzled gene expression increased significantly in the UUO model; AS-IV was associated with the downregulation of the expression of Wnt3, Wnt4, Frizzled4, p-LRP5, p-LRP6, disheveled, β-catenin, LEF-1, TCF-1, Snail, Jagged 1, Twist, MMP2, and MMP7 proteins in a concentration-dependent manner, while the expression of APC, CK1, and E-cadherin was increased. Conclusions: AS-IV effectively inhibits the up-regulation of proteins in the Wnt/β-catenin signaling pathway in UUO-model rats, indicating its possible inhibitory effects on renal interstitial fibrosis.

  13. Activated WNT signaling in postnatal SOX2-positive dental stem cells can drive odontoma formation

    Science.gov (United States)

    Xavier, Guilherme M.; Patist, Amanda L.; Healy, Chris; Pagrut, Ankita; Carreno, Gabriela; Sharpe, Paul T.; Pedro Martinez-Barbera, Juan; Thavaraj, Selvam; Cobourne, Martyn T.; Andoniadou, Cynthia L.

    2015-01-01

    In common with most mammals, humans form only two dentitions during their lifetime. Occasionally, supernumerary teeth develop in addition to the normal complement. Odontoma represent a small group of malformations containing calcified dental tissues of both epithelial and mesenchymal origin, with varying levels of organization, including tooth-like structures. The specific cell type responsible for the induction of odontoma, which retains the capacity to re-initiate de novo tooth development in postnatal tissues, is not known. Here we demonstrate that aberrant activation of WNT signaling by expression of a non-degradable form of β-catenin specifically in SOX2-positive postnatal dental epithelial stem cells is sufficient to generate odontoma containing multiple tooth-like structures complete with all dental tissue layers. Genetic lineage-tracing confirms that odontoma form in a similar manner to normal teeth, derived from both the mutation-sustaining epithelial stem cells and adjacent mesenchymal tissues. Activation of the WNT pathway in embryonic SOX2-positive progenitors results in ectopic expression of secreted signals that promote odontogenesis throughout the oral cavity. Significantly, the inductive potential of epithelial dental stem cells is retained in postnatal tissues, and up-regulation of WNT signaling specifically in these cells is sufficient to promote generation and growth of ectopic malformations faithfully resembling human odontoma. PMID:26411543

  14. Highly conserved molecular pathways, including Wnt signaling, promote functional recovery from spinal cord injury in lampreys.

    Science.gov (United States)

    Herman, Paige E; Papatheodorou, Angelos; Bryant, Stephanie A; Waterbury, Courtney K M; Herdy, Joseph R; Arcese, Anthony A; Buxbaum, Joseph D; Smith, Jeramiah J; Morgan, Jennifer R; Bloom, Ona

    2018-01-15

    In mammals, spinal cord injury (SCI) leads to dramatic losses in neurons and synaptic connections, and consequently function. Unlike mammals, lampreys are vertebrates that undergo spontaneous regeneration and achieve functional recovery after SCI. Therefore our goal was to determine the complete transcriptional responses that occur after SCI in lampreys and to identify deeply conserved pathways that promote regeneration. We performed RNA-Seq on lamprey spinal cord and brain throughout the course of functional recovery. We describe complex transcriptional responses in the injured spinal cord, and somewhat surprisingly, also in the brain. Transcriptional responses to SCI in lampreys included transcription factor networks that promote peripheral nerve regeneration in mammals such as Atf3 and Jun. Furthermore, a number of highly conserved axon guidance, extracellular matrix, and proliferation genes were also differentially expressed after SCI in lampreys. Strikingly, ~3% of differentially expressed transcripts belonged to the Wnt pathways. These included members of the Wnt and Frizzled gene families, and genes involved in downstream signaling. Pharmacological inhibition of Wnt signaling inhibited functional recovery, confirming a critical role for this pathway. These data indicate that molecular signals present in mammals are also involved in regeneration in lampreys, supporting translational relevance of the model.

  15. CUX1/Wnt signaling regulates Epithelial Mesenchymal Transition in EBV infected epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Malizia, Andrea P.; Lacey, Noreen [Clinical Research Centre, School of Medicine and Medical Science, University College Dublin. 21, Nelson Street. Dublin, 7. Ireland (Ireland); Walls, Dermot [School of Biotechnology, Dublin City University. Dublin, 9. Ireland (Ireland); Egan, Jim J. [Advanced Lung Disease and Lung Transplant Program, Mater Misericordiae University Hospital. 44, Eccles Street. Dublin, 7. Ireland (Ireland); Doran, Peter P., E-mail: peter.doran@ucd.ie [Clinical Research Centre, School of Medicine and Medical Science, University College Dublin. 21, Nelson Street. Dublin, 7. Ireland (Ireland)

    2009-07-01

    Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation and extra-cellular matrix protein deposition. EBV, localised to alveolar epithelial cells of pulmonary fibrosis patients is associated with a poor prognosis. A strategy based on microarray-differential gene expression analysis to identify molecular drivers of EBV-associated lung fibrosis was utilized. Alveolar epithelial cells were infected with EBV to identify genes whose expression was altered following TGF{beta}1-mediated lytic phase. EBV lytic reactivation by TGF{beta}1 drives a selective alteration in CUX1 variant (a) (NCBI accession number NM{sub 1}81552) expression, inducing activation of non-canonical Wnt pathway mediators, implicating it in Epithelial Mesenchymal Transition (EMT), the molecular event underpinning scar production in tissue fibrosis. The role of EBV in EMT can be attenuated by antiviral strategies and inhibition of Wnt signaling by using All-Trans Retinoic Acids (ATRA). Activation of non-canonical Wnt signaling pathway by EBV in epithelial cells suggests a novel mechanism of EMT via CUX1 signaling. These data present a framework for further description of the link between infectious agents and fibrosis, a significant disease burden.

  16. Crosstalk between Wnt/β-catenin and estrogen receptor signaling synergistically promotes osteogenic differentiation of mesenchymal progenitor cells.

    Directory of Open Access Journals (Sweden)

    Yanhong Gao

    Full Text Available Osteogenic differentiation from mesenchymal progenitor cells (MPCs are initiated and regulated by a cascade of signaling events. Either Wnt/β-catenin or estrogen signaling pathway has been shown to play an important role in regulating skeletal development and maintaining adult tissue homeostasis. Here, we investigate the potential crosstalk and synergy of these two signaling pathways in regulating osteogenic differentiation of MPCs. We find that the activation of estrogen receptor (ER signaling by estradiol (E2 or exogenously expressed ERα in MPCs synergistically enhances Wnt3A-induced early and late osteogenic markers, as well as matrix mineralization. The E2 or ERα-mediated synergy can be effectively blocked by ERα antagonist tamoxifen. E2 stimulation can enhance endochondral ossification of Wnt3A-transduced mouse fetal limb explants. Furthermore, exogenously expressed ERα significantly enhances the maturity and mineralization of Wnt3A-induced subcutaneous and intramuscular ectopic bone formation. Mechanistically, we demonstrate that E2 does not exert any detectable effect on β-catenin/Tcf reporter activity. However, ERα expression is up-regulated within the first 48h in AdWnt3A-transduced MPCs, whereas ERβ expression is significantly inhibited within 24h. Moreover, the key enzyme for the biosynthesis of estrogens aromatase is modulated by Wnt3A in a biphasic manner, up-regulated at 24h but reduced after 48h. Our results demonstrate that, while ER signaling acts synergistically with Wnt3A in promoting osteogenic differentiation, Wnt3A may crosstalk with ER signaling by up-regulating ERα expression and down-regulating ERβ expression in MPCs. Thus, the signaling crosstalk and synergy between these two pathways should be further explored as a potential therapeutic approach to combating bone and skeletal disorders, such as fracture healing and osteoporosis.

  17. Alteration of canonical and non-canonical WNT-signaling by crystalline silica in human lung epithelial cells.

    Science.gov (United States)

    Perkins, Timothy N; Dentener, Mieke A; Stassen, Frank R; Rohde, Gernot G; Mossman, Brooke T; Wouters, Emiel F M; Reynaert, Niki L

    2016-06-15

    Growth and development of the mature lung is a complex process orchestrated by a number of intricate developmental signaling pathways. Wingless-type MMTV-integration site (WNT) signaling plays critical roles in controlling branching morphogenesis cell differentiation, and formation of the conducting and respiratory airways. In addition, WNT pathways are often re-activated in mature lungs during repair and regeneration. WNT- signaling has been elucidated as a crucial contributor to the development of idiopathic pulmonary fibrosis as well as other hyper-proliferative lung diseases. Silicosis, a detrimental occupational lung disease caused by excessive inhalation of crystalline silica dust, is hallmarked by repeated cycles of damaging inflammation, epithelial hyperplasia, and formation of dense, hyalinized nodules of whorled collagen. However, mechanisms of epithelial cell hyperplasia and matrix deposition are not well understood, as most research efforts have focused on the pronounced inflammatory response. Microarray data from our previous studies has revealed a number of WNT-signaling and WNT-target genes altered by crystalline silica in human lung epithelial cells. In the present study, we utilize pathway analysis to designate connections between genes altered by silica in WNT-signaling networks. Furthermore, we confirm microarray findings by QRT-PCR and demonstrate both activation of canonical (β-catenin) and down-regulation of non-canonical (WNT5A) signaling in immortalized (BEAS-2B) and primary (PBEC) human bronchial epithelial cells. These findings suggest that WNT-signaling and cross-talk with other pathways (e.g. Notch), may contribute to proliferative, fibrogenic and inflammatory responses to silica in lung epithelial cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Wnt/β-Catenin Signaling Defines Organizing Centers that Orchestrate Growth and Differentiation of the Regenerating Zebrafish Caudal Fin

    Directory of Open Access Journals (Sweden)

    Daniel Wehner

    2014-02-01

    Full Text Available Zebrafish regenerate their fins via the formation of a population of progenitor cells, the blastema. Wnt/β-catenin signaling is essential for blastemal cell proliferation and patterning of the overlying epidermis. Yet, we find that β-catenin signaling is neither active in the epidermis nor the majority of the proliferative blastemal cells. Rather, tissue-specific pathway interference indicates that Wnt signaling in the nonproliferative distal blastema is required for cell proliferation in the proximal blastema, and signaling in cells lining the osteoblasts directs osteoblast differentiation. Thus, Wnt signaling regulates epidermal patterning, blastemal cell proliferation, and osteoblast maturation indirectly via secondary signals. Gene expression profiling, chromatin immunoprecipitation, and functional rescue experiments suggest that Wnt/β-catenin signaling acts through Fgf and Bmp signaling to control epidermal patterning, whereas retinoic acid and Hedgehog signals mediate its effects on blastemal cell proliferation. We propose that Wnt signaling orchestrates fin regeneration by defining organizing centers that instruct cellular behaviors of adjacent tissues.

  19. Signaling in fibrosis: TGF-β, WNT, and YAP/TAZ converge

    Directory of Open Access Journals (Sweden)

    Bram ePiersma

    2015-09-01

    Full Text Available Chronic organ injury leads to fibrosis and eventually organ failure. Fibrosis is characterized by excessive synthesis, remodeling and contraction of extracellular matrix produced by myofibroblasts. Myofibroblasts are the key cells in the pathophysiology of fibrotic disorders and their differentiation can be triggered by multiple stimuli. To develop anti-fibrotic therapies, it is of paramount importance to understand the molecular basis of the signaling pathways contributing to the activation and maintenance of myofibroblasts. Several signal transduction pathways such as TGF-β, Wnt, and more recently YAP/TAZ signaling, have been linked to the pathophysiology of fibrosis. Activation of the TGF-β1-induced SMAD complex results in the upregulation of genes important for myofibroblast function. Similarly, Wnt-stabilized β-catenin translocates to the nucleus and initiates transcription of its target genes. YAP and TAZ are two transcriptional co-activators from the Hippo signaling pathway that also rely on nuclear translocation for their functioning. These three signal transduction pathways have little molecular similarity but do share one principle: the cytosolic/nuclear regulation of its transcriptional activators. Past research on these pathways often focused on the isolated cascades without taking other signaling pathways into account. Recent developments show that parts of these pathways converge into an intricate network that governs the activation and maintenance of the myofibroblast phenotype. In this review we discuss the current understanding on the signal integration between the TGF-β, Wnt, and YAP/TAZ pathways in the development of organ fibrosis. Taking a network wide view on signal transduction will provide a better understanding on the complex and versatile processes that underlie the pathophysiology of fibrotic disorders.

  20. The Wnt Signaling Antagonist Kremen1 is Required for Development of Thymic Architecture

    Directory of Open Access Journals (Sweden)

    Masako Osada

    2006-01-01

    Full Text Available Wnt signaling has been reported to regulate thymocyte proliferation and selection at several stages during T cell ontogeny, as well as the expression of FoxN1 in thymic epithelial cells (TECs. Kremen1 (Krm1 is a negative regulator of the canonical Wnt signaling pathway, and functions together with the secreted Wnt inhibitor Dickkopf (Dkk by competing for the lipoprotein receptor-related protein (LRP-6 co-receptor for Wnts. Here krm1 knockout mice were used to examine krm1 expression in the thymus and its function in thymocyte and TEC development. krm1 expression was detected in both cortical and medullary TEC subsets, as well as in immature thymocyte subsets, beginning at the CD25+CD44+ (DN2 stage and continuing until the CD4+CD8+(DP stage. Neonatal mice show elevated expression of krm1 in all TEC subsets. krm1− / − mice exhibit a severe defect in thymic cortical architecture, including large epithelial free regions. Much of the epithelial component remains at an immature Keratin 5+ (K5 Keratin 8+(K8 stage, with a loss of defined cortical and medullary regions. A TOPFlash assay revealed a 2-fold increase in canonical Wnt signaling in TEC lines derived from krm1− / − mice, when compared with krm1+ / + derived TEC lines. Fluorescence activated cell sorting (FACS analysis of dissociated thymus revealed a reduced frequency of both cortical (BP1+EpCAM+ and medullary (UEA-1+ EpCAMhi epithelial subsets, within the krm1− / − thymus. Surprisingly, no change in thymus size, total thymocyte number or the frequency of thymocyte subsets was detected in krm1− / − mice. However, our data suggest that a loss of Krm1 leads to a severe defect in thymic architecture. Taken together, this study revealed a new role for Krm1 in proper development of thymic epithelium.

  1. Canonical WNT Signaling Enhances Stem Cell Expression in the Developing Heart Without a Corresponding Inhibition of Cardiogenic Differentiation

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    Martin, Lisa K.; Mezentseva, Nadejda V.; Bratoeva, Momka; Ramsdell, Ann F.; Eisenberg, Carol A.

    2011-01-01

    WNT signaling has been shown to influence the development of the heart. Although recent data suggested that canonical WNTs promote the emergence and expansion of cardiac progenitors in the pregastrula embryo, it has long been accepted that once gastrulation begins, canonical WNT signaling needs to be suppressed for cardiac development to proceed. Yet, this latter supposition appears to be odds with the expression of multiple canonical WNTs in the developing heart. The present study examining the effect of ectopic canonical WNT signaling on cardiogenesis in the developing frog was designed to test the hypothesis that heart formation is dependent on the inhibition of canonical WNT activity at the onset of gastrulation. Here we report that cardiac differentiation of explanted precardiac tissue from the dorsal marginal zone was not suppressed by exposure to WNT1 protein, although expression of Tbx5, Tbx20, and Nkx2.5 was selectively reduced. Pharmacological activation of WNT signaling in intact embryos using the GSK3 inhibitor SB415286 did not prevent the formation of an anatomically normal and functionally sound heart, with the only defect observed being lower levels of the cardiac transcription factor Nkx2.5. In both the explant and whole embryo studies, expression of muscle genes and proteins was unaffected by ectopic canonical WNT signaling. In contrast, canonical Wnt signaling upregulated expression of the cardiac stem cell marker c-kit and pluripotency genes Oct25 and Oct60. However, this regulatory stimulation of stem cells did not come at the expense of blocking cardiac progenitors from differentiating. PMID:21351874

  2. Wnt/β-catenin signaling in midbrain dopaminergic neuron specification and neurogenesis.

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    Joksimovic, Milan; Awatramani, Rajeshwar

    2014-02-01

    Loss of midbrain dopaminergic (mDA) neurons underlies the motor symptoms of Parkinson's disease. Towards cell replacement, studies have focused on mechanisms underlying embryonic mDA production, as a rational basis for deriving mDA neurons from stem cells. We will review studies of β-catenin, an obligate component of the Wnt cascade that is critical to mDA specification and neurogenesis. mDA neurons have a unique origin--the midbrain floor plate (FP). Unlike the hindbrain and spinal cord FP, the midbrain FP is highly neurogenic and Wnt/β-catenin signaling is critical to this difference in neurogenic potential. In β-catenin loss-of-function experiments, the midbrain FP resembles the hindbrain FP, and key mDA progenitor genes such as Otx2, Lmx1a, Msx1, and Ngn2 are downregulated whereas Shh is maintained. Accordingly, the neurogenic capacity of the midbrain FP is diminished, resulting in fewer mDA neurons. Conversely, in β-catenin gain-of-function experiments, the hindbrain FP expresses key mDA progenitor genes, and is highly neurogenic. Interestingly, when excessive β-catenin is supplied to the midbrain FP, less mDA neurons are produced suggesting that the dosage of Wnt/β-catenin signaling is critical. These studies of β-catenin have facilitated new protocols to derive mDA neurons from stem cells.

  3. Inhibition of WNT signaling in the bone marrow niche prevents the development of MDS in the Apcdel/+ MDS mouse model.

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    Stoddart, Angela; Wang, Jianghong; Hu, Chunmei; Fernald, Anthony A; Davis, Elizabeth M; Cheng, Jason X; Le Beau, Michelle M

    2017-06-01

    There is accumulating evidence that functional alteration(s) of the bone marrow (BM) microenvironment contribute to the development of some myeloid disorders, such as myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). In addition to a cell-intrinsic role of WNT activation in leukemia stem cells, WNT activation in the BM niche is also thought to contribute to the pathogenesis of MDS and AML. We previously showed that the Apc-haploinsufficient mice (Apcdel/+ ) model MDS induced by an aberrant BM microenvironment. We sought to determine whether Apc, a multifunctional protein and key negative regulator of the canonical β-catenin (Ctnnb1)/WNT-signaling pathway, mediates this disease through modulating WNT signaling, and whether inhibition of WNT signaling prevents the development of MDS in Apcdel/+ mice. Here, we demonstrate that loss of 1 copy of Ctnnb1 is sufficient to prevent the development of MDS in Apcdel/+ mice and that altered canonical WNT signaling in the microenvironment is responsible for the disease. Furthermore, the US Food and Drug Administration (FDA)-approved drug pyrvinium delays and/or inhibits disease in Apcdel/+ mice, even when it is administered after the presentation of anemia. Other groups have observed increased nuclear CTNNB1 in stromal cells from a high frequency of MDS/AML patients, a finding that together with our results highlights a potential new strategy for treating some myeloid disorders. © 2017 by The American Society of Hematology.

  4. Wnt signaling through the Ror receptor in the nervous system

    NARCIS (Netherlands)

    Petrova, Iveta M; Malessy, Martijn J; Verhaagen, J.; Fradkin, Lee G; Noordermeer, Jasprina N

    The receptor tyrosine kinase-like orphan receptor (Ror) proteins are conserved tyrosine kinase receptors that play roles in a variety of cellular processes that pattern tissues and organs during vertebrate and invertebrate development. Ror signaling is required for skeleton and neuronal development

  5. KCTD1 suppresses canonical Wnt signaling pathway by enhancing β-catenin degradation.

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    Xinxin Li

    Full Text Available The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1- and glycogen synthase kinase-3β (GSK-3β-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP. Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.

  6. Inhibitors of endocytosis prevent Wnt/Wingless signalling by reducing the level of basal β-catenin/Armadillo.

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    Gagliardi, Maria; Hernandez, Ana; McGough, Ian J; Vincent, Jean-Paul

    2014-11-15

    A key step in the canonical Wnt signalling pathway is the inhibition of GSK3β, which results in the accumulation of nuclear β-catenin (also known as CTNNB1), and hence regulation of target genes. Evidence suggests that endocytosis is required for signalling, yet its role and the molecular understanding remains unclear. A recent and controversial model suggests that endocytosis contributes to Wnt signalling by causing the sequestration of the ligand-receptor complex, including LRP6 and GSK3 to multivesicular bodies (MVBs), thus preventing GSK3β from accessing β-catenin. Here, we use specific inhibitors (Dynasore and Dyngo-4a) to confirm the essential role of endocytosis in Wnt/Wingless signalling in human and Drosophila cells. However, we find no evidence that, in Drosophila cells or wing imaginal discs, LRP6/Arrow traffics to MVBs or that MVBs are required for Wnt/Wingless signalling. Moreover, we show that activation of signalling through chemical blockade of GSK3β is prevented by endocytosis inhibitors, suggesting that endocytosis impacts on Wnt/Wingless signalling downstream of the ligand-receptor complex. We propose that, through an unknown mechanism, endocytosis boosts the resting pool of β-catenin upon which GSK3β normally acts. © 2014. Published by The Company of Biologists Ltd.

  7. Altered Expression of Wnt Signaling Pathway Components in Osteogenesis of Mesenchymal Stem Cells in Osteoarthritis Patients.

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    Pilar Tornero-Esteban

    Full Text Available Osteoarthritis (OA is characterized by altered homeostasis of joint cartilage and bone, whose functional properties rely on chondrocytes and osteoblasts, belonging to mesenchymal stem cells (MSCs. WNT signaling acts as a hub integrating and crosstalking with other signaling pathways leading to the regulation of MSC functions. The aim of this study was to evaluate the existence of a differential signaling between Healthy and OA-MSCs during osteogenesis.MSCs of seven OA patients and six healthy controls were isolated, characterised and expanded. During in vitro osteogenesis, cells were recovered at days 1, 10 and 21. RNA and protein content was obtained. Expression of WNT pathway genes was evaluated using RT-qPCR. Functional studies were also performed to study the MSC osteogenic commitment and functional and post-traslational status of β-catenin and several receptor tyrosine kinases.Several genes were downregulated in OA-MSCs during osteogenesis in vitro. These included soluble Wnts, inhibitors, receptors, co-receptors, several kinases and transcription factors. Basal levels of β-catenin were higher in OA-MSCs, but calcium deposition and expression of osteogenic genes was similar between Healthy and OA-MSCs. Interestingly an increased phosphorylation of p44/42 MAPK (ERK1/2 signaling node was present in OA-MSCs.Our results point to the existence in OA-MSCs of alterations in expression of Wnt pathway components during in vitro osteogenesis that are partially compensated by post-translational mechanisms modulating the function of other pathways. We also point the relevance of other signaling pathways in OA pathophysiology suggesting their role in the maintenance of joint homeostasis through modulation of MSC osteogenic potential.

  8. Altered Expression of Wnt Signaling Pathway Components in Osteogenesis of Mesenchymal Stem Cells in Osteoarthritis Patients.

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    Tornero-Esteban, Pilar; Peralta-Sastre, Ascensión; Herranz, Eva; Rodríguez-Rodríguez, Luis; Mucientes, Arkaitz; Abásolo, Lydia; Marco, Fernando; Fernández-Gutiérrez, Benjamín; Lamas, José Ramón

    2015-01-01

    Osteoarthritis (OA) is characterized by altered homeostasis of joint cartilage and bone, whose functional properties rely on chondrocytes and osteoblasts, belonging to mesenchymal stem cells (MSCs). WNT signaling acts as a hub integrating and crosstalking with other signaling pathways leading to the regulation of MSC functions. The aim of this study was to evaluate the existence of a differential signaling between Healthy and OA-MSCs during osteogenesis. MSCs of seven OA patients and six healthy controls were isolated, characterised and expanded. During in vitro osteogenesis, cells were recovered at days 1, 10 and 21. RNA and protein content was obtained. Expression of WNT pathway genes was evaluated using RT-qPCR. Functional studies were also performed to study the MSC osteogenic commitment and functional and post-traslational status of β-catenin and several receptor tyrosine kinases. Several genes were downregulated in OA-MSCs during osteogenesis in vitro. These included soluble Wnts, inhibitors, receptors, co-receptors, several kinases and transcription factors. Basal levels of β-catenin were higher in OA-MSCs, but calcium deposition and expression of osteogenic genes was similar between Healthy and OA-MSCs. Interestingly an increased phosphorylation of p44/42 MAPK (ERK1/2) signaling node was present in OA-MSCs. Our results point to the existence in OA-MSCs of alterations in expression of Wnt pathway components during in vitro osteogenesis that are partially compensated by post-translational mechanisms modulating the function of other pathways. We also point the relevance of other signaling pathways in OA pathophysiology suggesting their role in the maintenance of joint homeostasis through modulation of MSC osteogenic potential.

  9. (Pro)renin Receptor Is an Amplifier of Wnt/β-Catenin Signaling in Kidney Injury and Fibrosis.

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    Li, Zhen; Zhou, Lili; Wang, Yongping; Miao, Jinhua; Hong, Xue; Hou, Fan Fan; Liu, Youhua

    2017-08-01

    The (pro)renin receptor (PRR) is a transmembrane protein with multiple functions. However, its regulation and role in the pathogenesis of CKD remain poorly defined. Here, we report that PRR is a downstream target and an essential component of Wnt/β-catenin signaling. In mouse models, induction of CKD by ischemia-reperfusion injury (IRI), adriamycin, or angiotensin II infusion upregulated PRR expression in kidney tubular epithelium. Immunohistochemical staining of kidney biopsy specimens also revealed induction of renal PRR in human CKD. Overexpression of either Wnt1 or β-catenin induced PRR mRNA and protein expression in vitro Notably, forced expression of PRR potentiated Wnt1-mediated β-catenin activation and augmented the expression of downstream targets such as fibronectin, plasminogen activator inhibitor 1, and α-smooth muscle actin (α-SMA). Conversely, knockdown of PRR by siRNA abolished β-catenin activation. PRR potentiation of Wnt/β-catenin signaling did not require renin, but required vacuolar H+ ATPase activity. In the mouse model of IRI, transfection with PRR or Wnt1 expression vectors promoted β-catenin activation, aggravated kidney dysfunction, and worsened renal inflammation and fibrotic lesions. Coexpression of PRR and Wnt1 had a synergistic effect. In contrast, knockdown of PRR expression ameliorated kidney injury and fibrosis after IRI. These results indicate that PRR is both a downstream target and a crucial element in Wnt signal transmission. We conclude that PRR can promote kidney injury and fibrosis by amplifying Wnt/β-catenin signaling. Copyright © 2017 by the American Society of Nephrology.

  10. MMTV-Wnt1 and -DeltaN89beta-catenin induce canonical signaling in distinct progenitors and differentially activate Hedgehog signaling within mammary tumors.

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    Brigitte Teissedre

    Full Text Available Canonical Wnt/beta-catenin signaling regulates stem/progenitor cells and, when perturbed, induces many human cancers. A significant proportion of human breast cancer is associated with loss of secreted Wnt antagonists and mice expressing MMTV-Wnt1 and MMTV-DeltaN89beta-catenin develop mammary adenocarcinomas. Many studies have assumed these mouse models of breast cancer to be equivalent. Here we show that MMTV-Wnt1 and MMTV-DeltaN89beta-catenin transgenes induce tumors with different phenotypes. Using axin2/conductin reporter genes we show that MMTV-Wnt1 and MMTV-DeltaN89beta-catenin activate canonical Wnt signaling within distinct cell-types. DeltaN89beta-catenin activated signaling within a luminal subpopulation scattered along ducts that exhibited a K18(+ER(-PR(-CD24(highCD49f(low profile and progenitor properties. In contrast, MMTV-Wnt1 induced canonical signaling in K14(+ basal cells with CD24/CD49f profiles characteristic of two distinct stem/progenitor cell-types. MMTV-Wnt1 produced additional profound effects on multiple cell-types that correlated with focal activation of the Hedgehog pathway. We document that large melanocytic nevi are a hitherto unreported hallmark of early hyperplastic Wnt1 glands. These nevi formed along the primary mammary ducts and were associated with Hedgehog pathway activity within a subset of melanocytes and surrounding stroma. Hh pathway activity also occurred within tumor-associated stromal and K14(+/p63(+ subpopulations in a manner correlated with Wnt1 tumor onset. These data show MMTV-Wnt1 and MMTV-DeltaN89beta-catenin induce canonical signaling in distinct progenitors and that Hedgehog pathway activation is linked to melanocytic nevi and mammary tumor onset arising from excess Wnt1 ligand. They further suggest that Hedgehog pathway activation maybe a critical component and useful indicator of breast tumors arising from unopposed Wnt1 ligand.

  11. A Comprehensive Overview of Skeletal Phenotypes Associated with Alterations in Wnt/β-catenin Signaling in Humans and Mice.

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    Maupin, Kevin A; Droscha, Casey J; Williams, Bart O

    2013-03-01

    The Wnt signaling pathway plays key roles in differentiation and development and alterations in this signaling pathway are causally associated with numerous human diseases. While several laboratories were examining roles for Wnt signaling in skeletal development during the 1990s, interest in the pathway rose exponentially when three key papers were published in 2001-2002. One report found that loss of the Wnt co-receptor, Low-density lipoprotein related protein-5 (LRP5), was the underlying genetic cause of the syndrome Osteoporosis pseudoglioma (OPPG). OPPG is characterized by early-onset osteoporosis causing increased susceptibility to debilitating fractures. Shortly thereafter, two groups reported that individuals carrying a specific point mutation in LRP5 (G171V) develop high-bone mass. Subsequent to this, the causative mechanisms for these observations heightened the need to understand the mechanisms by which Wnt signaling controlled bone development and homeostasis and encouraged significant investment from biotechnology and pharmaceutical companies to develop methods to activate Wnt signaling to increase bone mass to treat osteoporosis and other bone disease. In this review, we will briefly summarize the cellular mechanisms underlying Wnt signaling and discuss the observations related to OPPG and the high-bone mass disorders that heightened the appreciation of the role of Wnt signaling in normal bone development and homeostasis. We will then present a comprehensive overview of the core components of the pathway with an emphasis on the phenotypes associated with mice carrying genetically engineered mutations in these genes and clinical observations that further link alterations in the pathway to changes in human bone.

  12. Membrane bound GSK-3 activates Wnt signaling through disheveled and arrow.

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    Anirudh G Mannava

    Full Text Available Wnt ligands and their downstream pathway components coordinate many developmental and cellular processes. In adults, they regulate tissue homeostasis through regulation of stem cells. Mechanistically, signal transduction through this pathway is complicated by pathway components having both positive and negative roles in signal propagation. Here we examine the positive role of GSK-3/Zw3 in promoting signal transduction at the plasma membrane. We find that targeting GSK-3 to the plasma membrane activates signaling in Drosophila embryos. This activation requires the presence of the co-receptor Arrow-LRP5/6 and the pathway activating protein Disheveled. Our results provide genetic evidence for evolutionarily conserved, separable roles for GSK-3 at the membrane and in the cytosol, and are consistent with a model where the complex cycles from cytosol to membrane in order to promote signaling at the membrane and to prevent it in the cytosol.

  13. Endogenous WNT Signals Mediate BMP-Induced and Spontaneous Differentiation of Epiblast Stem Cells and Human Embryonic Stem Cells

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    Dorota Kurek

    2015-01-01

    Full Text Available Therapeutic application of human embryonic stem cells (hESCs requires precise control over their differentiation. However, spontaneous differentiation is prevalent, and growth factors induce multiple cell types; e.g., the mesoderm inducer BMP4 generates both mesoderm and trophoblast. Here we identify endogenous WNT signals as BMP targets that are required and sufficient for mesoderm induction, while trophoblast induction is WNT independent, enabling the exclusive differentiation toward either lineage. Furthermore, endogenous WNT signals induce loss of pluripotency in hESCs and their murine counterparts, epiblast stem cells (EpiSCs. WNT inhibition obviates the need to manually remove differentiated cells to maintain cultures and improves the efficiency of directed differentiation. In EpiSCs, WNT inhibition stabilizes a pregastrula epiblast state with novel characteristics, including the ability to contribute to blastocyst chimeras. Our findings show that endogenous WNT signals function as hidden mediators of growth factor-induced differentiation and play critical roles in the self-renewal of hESCs and EpiSCs.

  14. Neuronal target identification requires AHA-1-mediated fine-tuning of Wnt signaling in C. elegans.

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    Jingyan Zhang

    2013-06-01

    Full Text Available Electrical synaptic transmission through gap junctions is a vital mode of intercellular communication in the nervous system. The mechanism by which reciprocal target cells find each other during the formation of gap junctions, however, is poorly understood. Here we show that gap junctions are formed between BDU interneurons and PLM mechanoreceptors in C. elegans and the connectivity of BDU with PLM is influenced by Wnt signaling. We further identified two PAS-bHLH family transcription factors, AHA-1 and AHR-1, which function cell-autonomously within BDU and PLM to facilitate the target identification process. aha-1 and ahr-1 act genetically upstream of cam-1. CAM-1, a membrane-bound receptor tyrosine kinase, is present on both BDU and PLM cells and likely serves as a Wnt antagonist. By binding to a cis-regulatory element in the cam-1 promoter, AHA-1 enhances cam-1 transcription. Our study reveals a Wnt-dependent fine-tuning mechanism that is crucial for mutual target cell identification during the formation of gap junction connections.

  15. Wnt/β-catenin signaling promotes aging-associated hair graying in mice.

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    Zhang, Zhihui; Lei, Mingxing; Xin, Haoran; Hu, Chunyan; Yang, Tian; Xing, Yizhan; Li, Yuhong; Guo, Haiying; Lian, Xiaohua; Deng, Fang

    2017-09-19

    Canities is an obvious sign of aging in mouse and human, shown as hair graying. Melanocytes in the hair follicle show cyclic activity with hair cycling, which transitions from anagen, catagen to telogen. How the hairs turn gray during aging is not completely uncovered. Here, by using immunostaining and LacZ staining in Dct-LacZ mice, we show that β-catenin is expressed in melanocytes during hair cycling. RT-PCR, western blot and immunostaining show that β-catenin expression is significantly increased in both anagen and telogen skin of aged mice, when compared to the anagen and telogen skin of young mice, respectively. Overexpression of Wnt10b not only accelerates hair follicle to enter anagen phase, but also promotes melanocytes differentiation in young adult mice (2-month old), with increased β-catenin expression in melanocytes at the secondary hair germ and matrix region of regenerated hair follicles. Overexpression of Wnt10b also promotes melanocyte progenitor cells differentiation in vitro . Our data suggest that increased Wnt signaling promotes excessive differentiation of melanocytes, leading to exhaustion of melanocyte stem cells and eventually canities in aged mice.

  16. Metformin enhances glucagon-like peptide 1 via cooperation between insulin and Wnt signaling.

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    Kim, Mi-Hyun; Jee, Jae-Hwan; Park, Sunyoung; Lee, Myung-Shik; Kim, Kwang-Won; Lee, Moon-Kyu

    2014-02-01

    One aspect of the effects of metformin on glucagon-like peptide (GLP)-1 might be associated with the mechanism by which the cross talk between insulin and Wnt signaling enhances GLP1 secretion, due to the action of metformin as an insulin sensitizer. However, this remains completely unknown. In this study, we have investigated the mechanisms of the action of metformin on cross talk between insulin and Wnt signaling. GLP1 enhancement by meformin was determined in human NCI-H716 intestinal L-cells and hyperglycemic db/db mice treated with metformin (0.25 and 0.5 mM and/or 12.5 mg/kg body weight) for 24 h and 2 months. Metformin increased GLP1 secretion in L-cells and db/db mice. Metformin stimulated the nuclear translocation of β-catenin and TOPflash reporter activity, and gene depletion of β-catenin or enhancement of mutation of transcription factor 7-like 2 binding site offset GLP1. In addition, insulin receptor substrate 2 gene depletion blocked metformin-enhanced β-catenin translocation. These effects were preceded by an increase in glucose utilization and calcium influx, the activation of calcium-dependent protein kinase, and, in turn, the activation of insulin signaling, and the inhibition of glycogen synthase kinase 3β, a potent inhibitor of β-catenin. Furthermore, high blood glucose levels were controlled via GLP1 receptor-dependent insulinotropic pathways in db/db mice, which were evidenced by the increase in GLP1 and insulin levels at 30 min after oral glucose loading and pancreatic insulinotropic gene expression. Our findings indicate that the cooperation between Wnt and its upstream insulin signaling pathways might be a novel and important mechanism underlying the effects of metformin on GLP1 production.

  17. Spatiotemporal Expression of Wnt/β-catenin Signaling during Morphogenesis and Odontogenesis of Deciduous Molar in Miniature Pig.

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    Wu, Xiaoshan; Li, Yan; Wang, Fu; Hu, Lei; Li, Yang; Wang, Jinsong; Zhang, Chunmei; Wang, Songlin

    2017-01-01

    The canonical Wnt/β-catenin signaling pathway has been shown to play essential roles in tooth initiation and early tooth development. However, the role of Wnt/β-catenin signaling in cusp patterning and crown calcification in large mammals are largely unknown. In our previous study, miniature pigs were used as the animal model due to the similarity of tooth anatomy and replacement pattern between miniature pig and human. Dynamic gene expression of third deciduous molar (DM3) in miniature pig at early stages was profiled using microarray method and expression of Wnt genes was significantly correlate with odontogenesis. In the present study, dynamic expression patterns of Wnt/β-catenin signaling genes of DM3 at cap, early bell and late bell (secretory) stage were identified. We found that Lef1 and Axin2 were expressed in the enamel knot and underlying mesenchyme regions. Meanwhile, Dkk1 was expressed in the peripheral and lower parts of dental papilla, thus forming the potential Wnt signaling gradient. We also found that β-Catenin, Axin2 and Lef1 were expressed strongly in undifferentiated cells of the inner enamel epithelium (IEE), but weakly in differentiated ameloblasts. Furthermore, we found that both Wnt signaling read-out gene Lef1 and the inhibitor Dkk1 were co-expressed in the pre-odontoblasts. In conclusion, the spatiotemporal distribution and potential gradient of Wnt signaling may contribute to cusp patterning and crown calcification. These data may yield insight into future study of precise control of crown morphogenesis and regeneration in large mammals.

  18. DKK1 mediated inhibition of Wnt signaling in postnatal mice leads to loss of TEC progenitors and thymic degeneration.

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    Masako Osada

    2010-02-01

    Full Text Available Thymic epithelial cell (TEC microenvironments are essential for the recruitment of T cell precursors from the bone marrow, as well as the subsequent expansion and selection of thymocytes resulting in a mature self-tolerant T cell repertoire. The molecular mechanisms, which control both the initial development and subsequent maintenance of these critical microenvironments, are poorly defined. Wnt signaling has been shown to be important to the development of several epithelial tissues and organs. Regulation of Wnt signaling has also been shown to impact both early thymocyte and thymic epithelial development. However, early blocks in thymic organogenesis or death of the mice have prevented analysis of a role of canonical Wnt signaling in the maintenance of TECs in the postnatal thymus.Here we demonstrate that tetracycline-regulated expression of the canonical Wnt inhibitor DKK1 in TECs localized in both the cortex and medulla of adult mice, results in rapid thymic degeneration characterized by a loss of DeltaNP63(+ Foxn1(+ and Aire(+ TECs, loss of K5K8DP TECs thought to represent or contain an immature TEC progenitor, decreased TEC proliferation and the development of cystic structures, similar to an aged thymus. Removal of DKK1 from DKK1-involuted mice results in full recovery, suggesting that canonical Wnt signaling is required for the differentiation or proliferation of TEC populations needed for maintenance of properly organized adult thymic epithelial microenvironments.Taken together, the results of this study demonstrate that canonical Wnt signaling within TECs is required for the maintenance of epithelial microenvironments in the postnatal thymus, possibly through effects on TEC progenitor/stem cell populations. Downstream targets of Wnt signaling, which are responsible for maintenance of these TEC progenitors may provide useful targets for therapies aimed at counteracting age associated thymic involution or the premature thymic

  19. Wnt Signaling Prevents the Aβ Oligomer-Induced Mitochondrial Permeability Transition Pore Opening Preserving Mitochondrial Structure in Hippocampal Neurons.

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    Arrázola, Macarena S; Ramos-Fernández, Eva; Cisternas, Pedro; Ordenes, Daniela; Inestrosa, Nibaldo C

    2017-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder mainly known for synaptic impairment and neuronal cell loss, affecting memory processes. Beside these damages, mitochondria have been implicated in the pathogenesis of AD through the induction of the mitochondrial permeability transition pore (mPTP). The mPTP is a non-selective pore that is formed under apoptotic conditions, disturbing mitochondrial structure and thus, neuronal viability. In AD, Aβ oligomers (Aβos) favor the opening of the pore, activating mitochondria-dependent neuronal cell death cascades. The Wnt signaling activated through the ligand Wnt3a has been described as a neuroprotective signaling pathway against amyloid-β (Aβ) peptide toxicity in AD. However, the mechanisms by which Wnt signaling prevents Aβos-induced neuronal cell death are unclear. We proposed here to study whether Wnt signaling protects neurons earlier than the late damages in the progression of the disease, through the preservation of the mitochondrial structure by the mPTP inhibition. To study specific events related to mitochondrial permeabilization we performed live-cell imaging from primary rat hippocampal neurons, and electron microscopy to analyze the mitochondrial morphology and structure. We report here that Wnt3a prevents an Aβos-induced cascade of mitochondrial events that leads to neuronal cell death. This cascade involves (a) mPTP opening, (b) mitochondrial swelling, (c) mitochondrial membrane potential loss and (d) cytochrome c release, thus leading to neuronal cell death. Furthermore, our results suggest that the activation of the Wnt signaling prevents mPTP opening by two possible mechanisms, which involve the inhibition of mitochondrial GSK-3β and/or the modulation of mitochondrial hexokinase II levels and activity. This study suggests a possible new approach for the treatment of AD from a mitochondrial perspective, and will also open new lines of study in the field of Wnt signaling in neuroprotection.

  20. The Tumor Suppressor BCL7B Functions in the Wnt Signaling Pathway.

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    Tomoko Uehara

    2015-01-01

    Full Text Available Human BCL7 gene family consists of BCL7A, BCL7B, and BCL7C. A number of clinical studies have reported that BCL7 family is involved in cancer incidence, progression, and development. Among them, BCL7B, located on chromosome 7q11.23, is one of the deleted genes in patients with Williams-Beuren syndrome. Although several studies have suggested that malignant diseases occurring in patients with Williams-Beuren syndrome are associated with aberrations in BCL7B, little is known regarding the function of this gene at the cellular level. In this study, we focused on bcl-7, which is the only homolog of BCL7 gene family in Caenorhabditis elegans, and analyzed bcl-7 deletion mutants. As a result, we found that bcl-7 is required for the asymmetric differentiation of epithelial seam cells, which have self-renewal properties as stem cells and divide asymmetrically through the WNT pathway. Distal tip cell development, which is regulated by the WNT pathway in Caenorhabditis elegans, was also affected in bcl-7-knockout mutants. Interestingly, bcl-7 mutants exhibited nuclear enlargement, reminiscent of the anaplastic features of malignant cells. Furthermore, in KATOIII human gastric cancer cells, BCL7B knockdown induced nuclear enlargement, promoted the multinuclei phenotype and suppressed cell death. In addition, this study showed that BCL7B negatively regulates the Wnt-signaling pathway and positively regulates the apoptotic pathway. Taken together, our data indicate that BCL7B/BCL-7 has some roles in maintaining the structure of nuclei and is involved in the modulation of multiple pathways, including Wnt and apoptosis. This study may implicate a risk of malignancies with BCL7B-deficiency, such as Williams-Beuren syndrome.

  1. Wnt and β-Catenin Signaling and Skeletal Muscle Myogenesis in Response to Muscle Damage and Resistance Exercise and Training

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    Dan Newmire

    2015-10-01

    Full Text Available The factors that regulate skeletal muscle hypertrophy in human adults in response to resistance training (RT has largely focused on endogenous endocrine responses. However, the endocrine response to RT as having an obligatory role in muscle hypertrophy has come under scrutiny, as other mechanisms and pathways seem to also be involved in up-regulating muscle protein synthesis (MPS. Skeletal muscle myogenesis is a multifactorial process of tissue growth and repair in response to resistance training is regulated by many factors.  As a result, satellite cell-fused myogenesis is a possible factor in skeletal muscle regeneration and hypertrophy in response to RT.  The Wnt family ligands interact with various receptors and activate different downstream signaling pathways and have been classified as either canonical (β-catenin dependent or non-canonical (β-catenin independent.  Wnt is secreted from numerous tissues in a paracrine fashion. The Wnt/β-catenin signaling pathway is a highly-regulated and intricate pathway that is essential to skeletal muscle myogenesis.  The canonical Wnt/β-catenin pathway may influence satellite cells to myogenic commitment, differentiation, and fusion into muscle fibers in response to injury or trauma, self-renewal, and normal basal turnover.  The current literature has shown that, in response mechanical overload from acute resistance exercise and chronic resistance training, that the Wnt/β-catenin signaling pathway is stimulated which may actuate the process of muscle repair and hypertrophy in response to exercise-induced muscle damage. The purpose of this review is to elaborate on the Wnt/β-catenin signaling  pathway, the current literature investigating the relationship of the Wnt/β-catenin pathway and its effects on myogenesis is response to muscle damage and resistance exercise and training.      Keywords: skeletal muscle, hypertrophy, myogenesis, cell signaling, protein synthesis, resistance

  2. Stage-Specific Regulation of Reprogramming to Induced Pluripotent Stem Cells by Wnt Signaling and T Cell Factor Proteins

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    Ritchie Ho

    2013-06-01

    Full Text Available Wnt signaling is intrinsic to mouse embryonic stem cell self-renewal. Therefore, it is surprising that reprogramming of somatic cells to induced pluripotent stem cells (iPSCs is not strongly enhanced by Wnt signaling. Here, we demonstrate that active Wnt signaling inhibits the early stage of reprogramming to iPSCs, whereas it is required and even stimulating during the late stage. Mechanistically, this biphasic effect of Wnt signaling is accompanied by a change in the requirement of all four of its transcriptional effectors: T cell factor 1 (Tcf1, Lef1, Tcf3, and Tcf4. For example, Tcf3 and Tcf4 are stimulatory early but inhibitory late in the reprogramming process. Accordingly, ectopic expression of Tcf3 early in reprogramming combined with its loss of function late enables efficient reprogramming in the absence of ectopic Sox2. Together, our data indicate that the stepwise process of reprogramming to iPSCs is critically dependent on the stage-specific control and action of all four Tcfs and Wnt signaling.

  3. Small-molecule inhibition of Wnt signaling abrogates dexamethasone-induced phenotype of primary human trabecular meshwork cells.

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    Ahadome, Sarah D; Zhang, Chi; Tannous, Elizabeth; Shen, James; Zheng, Jie J

    2017-08-01

    Trabecular meshwork (TM) cells are the governing regulators of the TM structure. When the functionality of these cells is impaired, the structure of the TM is perturbed which often results in increased ocular hypertension. High intraocular pressure is the most significant risk factor for steroid-induced glaucoma. Dexamethasone (Dex)-induced phenotype of TM cells is widely utilized as a model system to gain insight into mechanisms underlying damaged TM in glaucoma. In this study, to assess the possible role of abnormal Wnt signaling in steroid-induced glaucoma, we analyzed the effects of small-molecule Wnt signaling modulators on Dex-induced expression extracellular matrix proteins of primary human TM cells. While Dex-treated TM cells exhibited increased collagen and fibronectin expression, we found that Wnt signaling inhibitor 3235-0367 suppressed these Dex-induced effects. We therefore propose that Wnt signaling plays an important role in Dex-mediated impairment of TM cell functions. Moreover, the use of small-molecule Wnt signaling inhibitors to treat TM cells may provide an opportunity of restoring TM tissue in steroid-induced glaucoma. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Acetyl salicylic acid attenuates cardiac hypertrophy through Wnt signaling.

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    Gitau, Samuel Chege; Li, Xuelian; Zhao, Dandan; Guo, Zhenfeng; Liang, Haihai; Qian, Ming; Lv, Lifang; Li, Tianshi; Xu, Bozhi; Wang, Zhiguo; Zhang, Yong; Xu, Chaoqian; Lu, Yanjie; Du, Zhiming; Shan, Hongli; Yang, Baofeng

    2015-12-01

    Ventricular hypertrophy is a powerful and independent predictor of cardiovascular morbid events. The vascular properties of low-dose acetyl salicylic acid (aspirin) provide cardiovascular benefits through the irreversible inhibition of platelet cyclooxygenase 1; however, the possible anti-hypertrophic properties and potential mechanism of aspirin have not been investigated in detail. In this study, healthy wild-type male mice were randomly divided into three groups and subjected to transverse aortic constriction (TAC) or sham operation. The TAC-operated mice were treated with the human equivalent of low-dose aspirin (10 mg·kg(-1)·d(-1)); the remaining mice received an equal amount of phosphate buffered saline with 0.65% ethanol, which was used as a vehicle. A cardiomyocyte hypertrophy model induced by angiotensin II (10 nmol·L(-1)) was treated with the human equivalent of low (10 or 100 μmol·L(-1)) and high (1000 μmol·L(-1)) aspirin concentrations in plasma. Changes in the cardiac structure and function were assessed through echocardiography and transmission electron microscopy. Gene expression was determined through RT-PCR and western blot analysis. Results indicated that aspirin treatment abrogated the increased thickness of the left ventricular anterior and posterior walls, the swelling of mitochondria, and the increased surface area in in vivo and in vitro hypertrophy models. Aspirin also normalized the upregulated hypertrophic biomarkers, β-myosin heavy chain (β-MHC), atrial natriuretic peptide (ANP), and b-type natriuretic peptide (BNP). Aspirin efficiently reversed the upregulation of β-catenin and P-Akt expression and the TAC- or ANG II-induced downregulation of GSK-3β. Therefore, low-dose aspirin possesses significant anti-hypertrophic properties at clinically relevant concentrations for anti-thrombotic therapy. The downregulation of β-catenin and Akt may be the underlying signaling mechanism of the effects of aspirin.

  5. Cyclin G2 suppresses estrogen-mediated osteogenesis through inhibition of Wnt/β-catenin signaling.

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    Jinlan Gao

    Full Text Available Estrogen plays an important role in the maintenance of bone formation, and deficiency in the production of estrogen is directly linked to postmenopausal osteoporosis. To date, the underlying mechanisms of estrogen-mediated osteogenic differentiation are not well understood. In this study, a pluripotent mesenchymal precursor cell line C2C12 was used to induce osteogenic differentiation and subjected to detection of gene expressions or to manipulation of cyclin G2 expressions. C57BL/6 mice were used to generate bilateral ovariectomized and sham-operated mice for analysis of bone mineral density and protein expression. We identified cyclin G2, an unconventional member of cyclin, is involved in osteoblast differentiation regulated by estrogen in vivo and in vitro. In addition, the data showed that ectopic expression of cyclin G2 suppressed expression of osteoblast transcription factor Runx2 and osteogenic differentiation marker genes, as well as ALP activity and in vitro extracellular matrix mineralization. Mechanistically, Wnt/β-catenin signaling pathway is essential for cyclin G2 to inhibit osteogenic differentiation. To the best of our knowledge, the current study presents the first evidence that cyclin G2 serves as a negative regulator of both osteogenesis and Wnt/β-catenin signaling. Most importantly, the basal and 17β-estradiol-induced osteogenic differentiation was restored by overexpression of cyclin G2. These results taken together suggest that cyclin G2 may function as an endogenous suppressor of estrogen-induced osteogenic differentiation through inhibition of Wnt/β-catenin signaling.

  6. Efficacy of Mesenchymal Stem Cells in Suppression of Hepatocarcinorigenesis in Rats: Possible Role of Wnt Signaling

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    Abdel Aziz, Mohamed T

    2011-05-05

    Abstract Background The present study was conducted to evaluate the tumor suppressive effects of bone marrow derived mesenchymal stem cells (MSCs) in an experimental hepatocellular carcinoma (HCC) model in rats and to investigate the possible role of Wnt signaling in hepato-carcinogenesis. Methods Ninety rats were included in the study and were divided equally into: Control group, rats which received MSCs only, rats which received MSCs vehicle only, HCC group induced by diethylnitroseamine (DENA) and CCl 4 , rats which received MSCs after HCC induction, rats which received MSCs before HCC induction. Histopathological examination and gene expression of Wnt signaling target genes by real time, reverse transcription-polymerase chain reaction (RT-PCR) in rat liver tissue, in addition to serum levels of ALT, AST and alpha fetoprotein were performed in all groups. Results Histopathological examination of liver tissue from animals which received DENA-CCl4 only, revealed the presence of anaplastic carcinoma cells and macro-regenerative nodules type II with foci of large and small cell dysplasia. Administration of MSCs into rats after induction of experimental HCC improved the histopathological picture which showed minimal liver cell damage, reversible changes, areas of cell drop out filled with stem cells. Gene expression in rat liver tissue demonstrated that MSCs downregulated β-catenin, proliferating cell nuclear antigen (PCNA), cyclin D and survivin genes expression in liver tissues after HCC induction. Amelioration of the liver status after administration of MSCs has been inferred by the significant decrease of ALT, AST and Alpha fetoprotein serum levels. Administration of MSCs before HCC induction did not show any tumor suppressive or protective effect. Conclusions Administration of MSCs in chemically induced HCC has tumor suppressive effects as evidenced by down regulation of Wnt signaling target genes concerned with antiapoptosis, mitogenesis, cell proliferation

  7. Combined Wnt/β-Catenin, Met, and CXCL12/CXCR4 Signals Characterize Basal Breast Cancer and Predict Disease Outcome

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    Jane D. Holland

    2013-12-01

    Full Text Available Prognosis for patients with estrogen-receptor (ER-negative basal breast cancer is poor, and chemotherapy is currently the best therapeutic option. We have generated a compound-mutant mouse model combining the activation of β-catenin and HGF (Wnt-Met signaling, which produced rapidly growing basal mammary gland tumors. We identified the chemokine system CXCL12/CXCR4 as a crucial driver of Wnt-Met tumors, given that compound-mutant mice also deficient in the CXCR4 gene were tumor resistant. Wnt-Met activation rapidly expanded a population of cancer-propagating cells, in which the two signaling systems control different functions, self-renewal and differentiation. Molecular therapy targeting Wnt, Met, and CXCR4 in mice significantly delayed tumor development. The expression of a Wnt-Met 322 gene signature was found to be predictive of poor survival of human patients with ER-negative breast cancers. Thus, targeting CXCR4 and its upstream activators, Wnt and Met, might provide an efficient strategy for breast cancer treatment.

  8. IL-1β-induced, matrix metalloproteinase-3-regulated proliferation of embryonic stem cell-derived odontoblastic cells is mediated by the Wnt5 signaling pathway

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    Ozeki, Nobuaki; Hase, Naoko; Hiyama, Taiki; Yamaguchi, Hideyuki; Kawai, Rie [Department of Endodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi 464-8651 (Japan); Kondo, Ayami [Department of Medicinal Biochemistry, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650 (Japan); Nakata, Kazuhiko [Department of Endodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi 464-8651 (Japan); Mogi, Makio, E-mail: makio@dpc.agu.ac.jp [Department of Medicinal Biochemistry, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650 (Japan)

    2014-10-15

    We previously established a method for differentiating induced pluripotent stem cells and embryonic stem (ES) cells into α2 integrin-positive odontoblast-like cells. We also reported that interleukin (IL)-1β induces matrix metalloproteinase (MMP)-3-regulated cell proliferation and suppresses apoptosis in these cells, suggesting that MMP-3 plays a potentially unique physiological role in the regeneration of odontoblast-like cells. Here, we examined whether up-regulation of MMP-3 activity by IL-1β was mediated by Wnt signaling and led to increased proliferation of odontoblast-like cells. IL-1β increased mRNA and protein levels of Wnt5a, Wnt5b and the Wnt receptor Lrp5. Exogenous Wnt5a and Wnt5b were found to increase MMP-3 mRNA, protein and activity, and interestingly the rate of proliferation in these cells. Treatment with siRNAs against Wnt5a, Wnt5b and Lrp5 suppressed the IL-1β-induced increase in MMP-3 expression and suppressed cell proliferation, an effect rescued by application of exogenous Wnt5. These results demonstrate the sequential involvement of Wnt5, Lrp5 and MMP-3 in effecting IL-1β-induced proliferation of ES cell-derived odontoblast-like cells. - Highlights: • IL-1β induces Wnt5, Lrp5/Fzd9 and MMP-3 in ES cell-derived odontoblast-like cells. • IL-1β-induced Wnt5 expression results in increased cell proliferation. • Exogenous Wnt5 increases MMP-3 activity and cell proliferation. • Exogenous Wnt5 rescues IL-1β-driven proliferation with anti-Wnt5 siRNA suppression. • IL-1β-induced cell proliferation involves Wnt5, Lrp5, and MMP-3 sequentially.

  9. Melatonin attenuates titanium particle-induced osteolysis via activation of Wnt/β-catenin signaling pathway.

    Science.gov (United States)

    Ping, Zichuan; Hu, Xuanyang; Wang, Liangliang; Shi, Jiawei; Tao, Yunxia; Wu, Xiexing; Hou, Zhenyang; Guo, Xiaobin; Zhang, Wen; Yang, Huilin; Xu, Yaozeng; Wang, Zhirong; Geng, Dechun

    2017-03-15

    Wear debris-induced inhibition of bone regeneration and extensive bone resorption were common features in peri-prosthetic osteolysis (PPO). Here, we investigated the effect of melatonin on titanium particle-stimulated osteolysis in a murine calvariae model and mouse-mesenchymal-stem cells (mMSCs) culture system. Melatonin inhibited titanium particle-induced osteolysis and increased bone formation at osteolytic sites, confirmed by radiological and histomorphometric data. Furthermore, osteoclast numbers decreased dramatically in the low- and high-melatonin administration mice, as respectively, compared with the untreated animals. Melatonin alleviated titanium particle-induced depression of osteoblastic differentiation and mineralization in mMSCs. Mechanistically, melatonin was found to reduce the degradation of β-catenin, levels of which were decreased in presence of titanium particles both in vivo and in vitro. To further ensure whether the protective effect of melatonin was mediated by the Wnt/β-catenin signaling pathway, ICG-001, a selective β-catenin inhibitor, was added to the melatonin-treated groups and was found to attenuate the effect of melatonin on mMSC mineralization. We also demonstrated that melatonin modulated the balance between receptor activator of nuclear factor kappa-B ligand and osteoprotegerin via activation of Wnt/β-catenin signaling pathway. These findings strongly suggest that melatonin represents a promising candidate in the treatment of PPO. Peri-prosthetic osteolysis, initiated by wear debris-induced inhibition of bone regeneration and extensive bone resorption, is the leading cause for implant failure and reason for revision surgery. In the current study, we demonstrated for the first time that melatonin can induce bone regeneration and reduce bone resorption at osteolytic sites caused by titanium-particle stimulation. These effects might be mediated by activating Wnt/β-catenin signaling pathway and enhancing osteogenic

  10. N-cadherin negatively regulates osteoblast proliferation and survival by antagonizing Wnt, ERK and PI3K/Akt signalling.

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    Eric Haÿ

    Full Text Available BACKGROUND: Osteoblasts are bone forming cells that play an essential role in osteogenesis. The elucidation of the mechanisms that control osteoblast number is of major interest for the treatment of skeletal disorders characterized by abnormal bone formation. Canonical Wnt signalling plays an important role in the control of osteoblast proliferation, differentiation and survival. Recent studies indicate that the cell-cell adhesion molecule N-cadherin interacts with the Wnt co-receptors LRP5/6 to regulate osteoblast differentiation and bone accrual. The role of N-cadherin in the control of osteoblast proliferation and survival remains unknown. METHODS AND PRINCIPAL FINDINGS: Using murine MC3T3-E1 osteoblastic cells and N-cadherin transgenic mice, we demonstrate that N-cadherin overexpression inhibits cell proliferation in vitro and in vivo. The negative effect of N-cadherin on cell proliferation results from decreased Wnt, ERK and PI3K/Akt signalling and is restored by N-cadherin neutralizing antibody that antagonizes N-cadherin-LRP5 interaction. Inhibition of Wnt signalling using DKK1 or Sfrp1 abolishes the ability of N-cadherin blockade to restore ERK and PI3K signalling and cell proliferation, indicating that the altered cell growth in N-cadherin overexpressing cells is in part secondary to alterations in Wnt signalling. Consistently, we found that N-cadherin overexpression inhibits the expression of Wnt3a ligand and its downstream targets c-myc and cyclin D1, an effect that is partially reversed by N-cadherin blockade. We also show that N-cadherin overexpression decreases osteoblast survival in vitro and in vivo. This negative effect on cell survival results from inhibition of PI3K/Akt signalling and increased Bax/Bcl-2, a mechanism that is rescued by Wnt3a. CONCLUSION: The data show that N-cadherin negatively controls osteoblast proliferation and survival via inhibition of autocrine/paracrine Wnt3a ligand expression and attenuation of Wnt

  11. Long-Term Expansion, Enhanced Chondrogenic Potential, and Suppression of Endochondral Ossification of Adult Human MSCs via WNT Signaling Modulation

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    Roberto Narcisi

    2015-03-01

    Full Text Available Mesenchymal stem cells (MSCs are a potential source of chondrogenic cells for the treatment of cartilage disorders, but loss of chondrogenic potential during in vitro expansion and the propensity of cartilage to undergo hypertrophic maturation impede their therapeutic application. Here we report that the signaling protein WNT3A, in combination with FGF2, supports long-term expansion of human bone marrow-derived MSCs. The cells retained their chondrogenic potential and other phenotypic and functional properties of multipotent MSCs, which were gradually lost in the absence of WNT3A. Moreover, we discovered that endogenous WNT signals are the main drivers of the hypertrophic maturation that follows chondrogenic differentiation. Inhibition of WNT signals during differentiation prevented calcification and maintained cartilage properties following implantation in a mouse model. By maintaining potency during expansion and preventing hypertrophic maturation following differentiation, the modulation of WNT signaling removes two major obstacles that impede the clinical application of MSCs in cartilage repair.

  12. Long-Term In Vitro Expansion of Salivary Gland Stem Cells Driven by Wnt Signals

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    Martti Maimets

    2016-01-01

    Full Text Available Adult stem cells are the ultimate source for replenishment of salivary gland (SG tissue. Self-renewal ability of stem cells is dependent on extrinsic niche signals that have not been unraveled for the SG. The ductal compartment in SG has been identified as the location harboring stem cells. Here, we report that rare SG ductal EpCAM+ cells express nuclear β-catenin, indicating active Wnt signaling. In cell culture experiments, EpCAMhigh cells respond potently to Wnt signals stimulating self-renewal and long-term expansion of SG organoids, containing all differentiated SG cell types. Conversely, Wnt inhibition ablated long-term organoid cultures. Finally, transplantation of cells pre-treated with Wnt agonists into submandibular glands of irradiated mice successfully and robustly restored saliva secretion and increased the number of functional acini in vivo. Collectively, these results identify Wnt signaling as a key driver of adult SG stem cells, allowing extensive in vitro expansion and enabling restoration of SG function upon transplantation.

  13. PLD1 regulates Xenopus convergent extension movements by mediating Frizzled7 endocytosis for Wnt/PCP signal activation.

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    Lee, Hyeyoon; Lee, Seung Joon; Kim, Gun-Hwa; Yeo, Inchul; Han, Jin-Kwan

    2016-03-01

    Phospholipase D (PLD) is involved in the regulation of receptor-associated signaling, cell movement, cell adhesion and endocytosis. However, its physiological role in vertebrate development remains poorly understood. In this study, we show that PLD1 is required for the convergent extension (CE) movements during Xenopus gastrulation by activating Wnt/PCP signaling. Xenopus PLD1 protein is specifically enriched in the dorsal region of Xenopus gastrula embryo and loss or gain-of-function of PLD1 induce defects in gastrulation and CE movements. These defective phenotypes are due to impaired regulation of Wnt/PCP signaling pathway. Biochemical and imaging analysis using Xenopus tissues reveal that PLD1 is required for Fz7 receptor endocytosis upon Wnt11 stimulation. Moreover, we show that Fz7 endocytosis depends on dynamin and regulation of GAP activity of dynamin by PLD1 via its PX domain is crucial for this process. Taken together, our results suggest that PLD1 acts as a new positive mediator of Wnt/PCP signaling by promoting Wnt11-induced Fz7 endocytosis for precise regulation of Xenopus CE movements. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Morinda citrifolia Leaf Extract Enhances Osteogenic Differentiation Through Activation of Wnt/β-Catenin Signaling.

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    Gu, Hanna; Boonanantanasarn, Kanitsak; Kang, Moonkyu; Kim, Ikhwi; Woo, Kyung Mi; Ryoo, Hyun-Mo; Baek, Jeong-Hwa

    2017-10-05

    Morinda citrifolia (Noni) leaf is an herbal medicine with application in the domestic treatment of a broad range of conditions, including bone fracture and luxation. However, the basic mechanism underlying the stimulation of osteogenic differentiation by Noni leaf extract remains poorly understood. This study aimed to examine the effect of this extract on osteogenic differentiation and the mechanism by which Noni leaf extract enhances osteogenic differentiation. Aqueous extract of Noni leaves was prepared, and rutin and kaempferol-3-O-rutinoside were identified to be two of its major components. C2C12 and human periodontal ligament (hPDL) cells were used to study the effect of Noni. Noni did not show cytotoxicity at a concentration range of 0.015%-1.0% (w/v%) and significantly enhanced the activity of alkaline phosphatase (ALP) and expression levels of osteoblast differentiation markers, including Runx2, ALP, osterix, and osteocalcin, bone morphogenetic protein 2, Wnt3a, and β-catenin. In addition, Noni enhanced the matrix mineralization of hPDL cells. In the signaling pathways, Noni increased the phosphorylation levels of Akt and GSK3β and nuclear translocation and transcriptional activity of β-catenin, which were attenuated by the addition of Dkk-1, a Wnt inhibitor, or LY294002, a PI3K inhibitor. These results suggest that Noni leaf extract enhances osteogenic differentiation through the PI3K/Akt-dependent activation of Wnt/β-catenin signaling. Noni leaf extract might be a novel alternative medicine for bone and periodontal regeneration in patients with periodontal diseases.

  15. BMP and TGF-β pathway mediators are critical upstream regulators of Wnt signaling during midbrain dopamine differentiation in human pluripotent stem cells.

    Science.gov (United States)

    Cai, Jingli; Schleidt, Stephanie; Pelta-Heller, Joshua; Hutchings, Danielle; Cannarsa, Gregory; Iacovitti, Lorraine

    2013-04-01

    Although many laboratories currently use small molecule inhibitors of the BMP (Dorsomorphin/DM) and TGF-β (SB431542/SB) signaling pathways in protocols to generate midbrain dopamine (mDA) neurons from hES and hiPS cells, until now, these substances have not been thought to play a role in the mDA differentiation process. We report here that the transient inhibition of constitutive BMP (pSMADs 1, 5, 8) signaling, either alone or in combination with TGF-β inhibition (pSMADs 2, 3), is critically important in the upstream regulation of Wnt1-Lmx1a signaling in mDA progenitors. We postulate that the mechanism via which DM or DM/SB mediates these effects involves the up-regulation in SMAD-interacting protein 1 (SIP1), which results in greater repression of the Wnt antagonist, secreted frizzled related protein 1 (Sfrp1) in stem cells. Accordingly, knockdown of SIP1 reverses the inductive effects of DM/SB on mDA differentiation while Sfrp1 knockdown/inhibition mimics DM/SB. The rise in Wnt1-Lmx1a levels in SMAD-inhibited cultures is, however, accompanied by a reciprocal down-regulation in SHH-Foxa2 levels leading to the generation of few TH+ neurons that co-express Foxa2. If however, exogenous SHH/FGF8 is added along with SMAD inhibitors, equilibrium in these two important pathways is achieved such that authentic (Lmx1a+Foxa2+TH+) mDA neuron differentiation is promoted while alternate cell fates are suppressed in stem cell cultures. These data indicate that activators/inhibitors of BMP and TGF-β signaling play a critical upstream regulatory role in the mDA differentiation process in human pluripotent stem cells. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Therapeutic effects of antibiotic drug tigecycline against cervical squamous cell carcinoma by inhibiting Wnt/β-catenin signaling

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    Li, Hui; Jiao, Shun [Department of Obstetrics and Gynaecology, JingZhou Hospital Affiliated to Huazhong University of Science and Technology, Jingzhou (China); Li, Xin [Department of Obstetrics and Gynaecology, RenMin Hospital of Wuhan University, Wuhan (China); Banu, Hasina; Hamal, Shreejana [Department of Clinical Medicine, Medical School of Yangtze University, Jingzhou (China); Wang, Xianrong, E-mail: Dr.XianRong.Wang@hotmail.com [Department of Obstetrics and Gynaecology, JingZhou Hospital Affiliated to Huazhong University of Science and Technology, Jingzhou (China)

    2015-11-06

    Aberrant activation of the Wnt/β-catenin signaling pathway is common in human cervical cancers and has great potential therapeutic value. We show that tigecycline, a FDA-approved antibiotic drug, targets cervical squamous cell carcinoma through inhibiting Wnt/β-catenin signaling pathway. Tigecycline is effective in inducing apoptosis, inhibiting proliferation and anchorage-independent colony formation of Hela cells. The inhibitory effects of tigecycline are further enhanced upon combination with paclitaxel, a most commonly used chemotherapeutic drug for cervical cancer. In a cervical xenograft model, tigecycline inhibits tumor growth as a single agent and its combination with paclitaxel significantly inhibits more tumor growth throughout the duration of treatment. We further show that tigecycline decreases level of both cytoplasmic and nuclear β-catenin and suppressed Wnt/β-catenin-mediated transcription through increasing levels of Axin 1 in Hela cells. In addition, stabilization or overexpression of β-catenin using pharmacological and genetic approaches abolished the effects of tigecycline in inhibiting proliferation and inducing apoptosis of Hela cells. Our study suggests that tigecycline is a useful addition to the treatment armamentarium for cervical cancer and targeting Wnt/β-catenin represents a potential therapeutic strategy in cervical cancer. - Highlights: • We repurposed the antibiotic drug tigecycline for cervical cancer treatment. • Tigecycline is effectively against cervical cancer cells in vitro and in vivo. • Combination of tigecycline and paclitaxel is synergistic in targeting Hela cells. • Tigecycline acts on Hela cells through inhibiting Wnt/β-catenin signaling.

  17. Dullard/Ctdnep1 modulates WNT signalling activity for the formation of primordial germ cells in the mouse embryo.

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    Satomi S Tanaka

    Full Text Available Dullard/Ctdnep1 is a member of the serine/threonine phosphatase family of the C-terminal domain of eukaryotic RNA polymerase II. Embryos lacking Dullard activity fail to form primordial germ cells (PGCs. In the mouse, the formation of PGCs is influenced by BMP4 and WNT3 activity. Although Dullard is reputed to negatively regulate BMP receptor function, in this study we found mutations in Dullard had no detectable effect on BMP4 and p-Smad activity. Furthermore Dullard mutations did not influence the dosage-dependent inductive effect of Bmp4 in PGC formation. However, Dullard may function as a positive regulator of WNT signalling. Combined loss of one copy each of Dullard and Wnt3 had a synergistic effect on the reduction of PGC numbers in the compound heterozygous embryo. In addition, loss of Dullard function was accompanied by down-regulation of WNT/β-catenin signalling activity and a reduction in the level of Dishevelled 2 (Dvl2. Therefore, Dullard may play a role in the fine-tuning of WNT signalling activity by modulating the expression of ligands/antagonists and the availability of Dvl2 protein during specification of the germ cell lineage.

  18. Lineage specification of parietal epithelial cells requires β-catenin/Wnt signaling.

    Science.gov (United States)

    Grouls, Stephan; Iglesias, Diana Margarita; Wentzensen, Nicolas; Moeller, Marcus Johannes; Bouchard, Maxime; Kemler, Rolf; Goodyer, Paul; Niggli, Felix; Gröne, Hermann-Josef; Kriz, Wilhelm; Koesters, Robert

    2012-01-01

    β-Catenin/Wnt signaling is essential during early inductive stages of kidney development, but its role during postinductive stages of nephron development and maturation is not well understood. In this study, we used Pax8Cre mice to target β-catenin deficiency to renal epithelial cells at the late S-shaped body stage and the developing collecting ducts. The conditional β-catenin knockout mice formed abnormal kidneys and had reduced renal function. The kidneys were hypoplastic with a thin cortex; a superficial layer of tubules was missing. A high proportion of glomeruli had small, underdeveloped capillary tufts. In these glomeruli, well differentiated podocytes replaced parietal epithelial cells in Bowman's capsule; capillaries toward the outer aspect of these podocytes mimicked the formation of glomerular capillaries. Tracing nephrogenesis in embryonic conditional β-catenin knockout mice revealed that these "parietal podocytes" derived from precursor cells in the parietal layer of the S-shaped body by direct lineage switch. Taken together, these findings demonstrate that β-catenin/Wnt signaling is important during the late stages of nephrogenesis and for the lineage specification of parietal epithelial cells.

  19. miR-612 suppresses the stemness of liver cancer via Wnt/β-catenin signaling

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jun [Liver Cancer Institute and Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai 200032 (China); Tao, Zhong-Hua [Department of Medical Oncology, Shanghai Cancer Center, Fudan University, Shanghai 200032 (China); Wen, Duo; Wan, Jin-Liang; Liu, Dong-Li; Zhang, Shu; Cui, Jie-Feng; Sun, Hui-Chuan; Wang, Lu [Liver Cancer Institute and Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai 200032 (China); Zhou, Jian; Fan, Jia [Liver Cancer Institute and Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai 200032 (China); Institute of Biomedical Sciences of Fudan University, Shanghai 200032 (China); Wu, Wei-Zhong, E-mail: wu.weizhong@zs-hospital.sh.cn [Liver Cancer Institute and Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai 200032 (China)

    2014-04-25

    Highlights: • miR-612 suppresses tumorsphere and clone formation of HCC cells. • miR-612 reduces drug resistance of HCC cells. • miR-612 suppresses tumorigenesis of HCC in NOD/SCID mice. • miR-612 inhibits an invasive frontier of HCC xenografts. • miR-612 suppresses Wnt/β-catenin signaling. - Abstract: Previous research showed that microRNA-612 (miR-612) has inhibitory effects on cell proliferation, migration, invasion, and metastasis of hepatocellular carcinoma (HCC). AKT2 was confirmed to be a direct target of miR-612, through which the epithelial–mesenchymal transition (EMT) and metastasis of HCC were inhibited. Our present findings reveal that miR-612 is able to suppress the stemness of HCC by reducing the number and size of tumorspheres as well as clone formation in soft agar, and to relieve drug resistance to cisplatin and 5-fluorouracil. In addition, miR-612 hampered the capacity of tumorigenesis in NOD/SCID mice and redistributed the tumor invasive frontier of miR-612-modulating cells. Finally, our findings suggest that Wnt/β-catenin signaling is required in the regulation of EMT-associated stem cell-like traits by miR-612.

  20. Altered Wnt Signaling Pathway in Cognitive Impairment Caused by Chronic Intermittent Hypoxia: Focus on Glycogen Synthase Kinase-3β and β-catenin

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    Yue-Ying Pan

    2016-01-01

    Conclusions: Wnt/β-catenin signaling pathway abnormalities possibly play an important role in the development of cognitive deficits among mice exposed to CIH and that LiCl might attenuate CIH-induced cognitive impairment via Wnt/β-catenin signaling pathway.

  1. Wnt/beta-catenin signaling plays an essential role in activation of odontogenic mesenchyme during early tooth development.

    Science.gov (United States)

    Chen, Jianquan; Lan, Yu; Baek, Jin-A; Gao, Yang; Jiang, Rulang

    2009-10-01

    Classical tissue recombination studies demonstrated that initiation of tooth development depends on activation of odontogenic potential in the mesenchyme by signals from the presumptive dental epithelium. Although several members of the Wnt family of signaling molecules are expressed in the presumptive dental epithelium at the beginning of tooth initiation, whether Wnt signaling is directly involved in the activation of the odontogenic mesenchyme has not been characterized. In this report, we show that tissue-specific inactivation of beta-catenin, a central component of the canonical Wnt signaling pathway, in the developing tooth mesenchyme caused tooth developmental arrest at the bud stage in mice. We show that mesenchymal beta-catenin function is required for expression of Lef1 and Fgf3 in the developing tooth mesenchyme and for induction of primary enamel knot in the developing tooth epithelium. Expression of Msx1 and Pax9, two essential tooth mesenchyme transcription factors downstream of Bmp and Fgf signaling, respectively, were not altered in the absence of beta-catenin in the tooth mesenchyme. Moreover, we found that constitutive stabilization of beta-catenin in the developing palatal mesenchyme induced aberrant palatal epithelial invaginations that resembled early tooth buds both morphologically and in epithelial molecular marker expression, but without activating expression of Msx1 and Pax9 in the mesenchyme. Together, these results indicate that activation of the mesenchymal odontogenic program during early tooth development requires concerted actions of Bmp, Fgf and Wnt signaling from the presumptive dental epithelium to the mesenchyme.

  2. Wnt/ß-catenin signalling and the dynamics of fate decisions in early mouse embryos and embryonic stem (ES) cells.

    Science.gov (United States)

    Muñoz-Descalzo, Silvia; Hadjantonakis, Anna-Katerina; Arias, Alfonso Martinez

    2015-12-01

    Wnt/ß-catenin signalling is a widespread cell signalling pathway with multiple roles during vertebrate development. In mouse embryonic stem (mES) cells, there is a dual role for ß-catenin: it promotes differentiation when activated as part of the Wnt/ß-catenin signalling pathway, and promotes stable pluripotency independently of signalling. Although mES cells resemble the preimplantation epiblast progenitors, the first requirement for Wnt/ß-catenin signalling during mouse development has been reported at implantation [1,2]. The relationship between ß-catenin and pluripotency and that of mES cells with epiblast progenitors suggests that ß-catenin might have a functional role during preimplantation development. Here we summarize the expression and function of Wnt/ß-catenin signalling elements during the early stages of mouse development and consider the reasons why the requirement in ES cells do not reflect the embryo. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  3. Mutations in LRP5 cause primary osteoporosis without features of OI by reducing Wnt signaling activity

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    Korvala Johanna

    2012-04-01

    Full Text Available Abstract Background Primary osteoporosis is a rare childhood-onset skeletal condition whose pathogenesis has been largely unknown. We have previously shown that primary osteoporosis can be caused by heterozygous missense mutations in the Low-density lipoprotein receptor-related protein 5 (LRP5 gene, and the role of LRP5 is further investigated here. Methods LRP5 was analyzed in 18 otherwise healthy children and adolescents who had evidence of osteoporosis (manifested as reduced bone mineral density i.e. BMD, recurrent peripheral fractures and/or vertebral compression fractures but who lacked the clinical features of osteogenesis imperfecta (OI or other known syndromes linked to low BMD. Also 51 controls were analyzed. Methods used in the genetic analyses included direct sequencing and multiplex ligation-dependent probe amplification (MLPA. In vitro studies were performed using luciferase assay and quantitative real-time polymerase chain reaction (qPCR to examine the effect of two novel and three previously identified mutations on the activity of canonical Wnt signaling and on expression of tryptophan hydroxylase 1 (Tph1 and 5-hydroxytryptamine (5-Htr1b. Results Two novel LRP5 mutations (c.3446 T > A; p.L1149Q and c.3553 G > A; p.G1185R were identified in two patients and their affected family members. In vitro analyses showed that one of these novel mutations together with two previously reported mutations (p.C913fs, p.R1036Q significantly reduced the activity of the canonical Wnt signaling pathway. Such reductions may lead to decreased bone formation, and could explain the bone phenotype. Gut-derived Lrp5 has been shown to regulate serotonin synthesis by controlling the production of serotonin rate-limiting enzyme, Tph1. LRP5 mutations did not affect Tph1 expression, and only one mutant (p.L1149Q reduced expression of serotonin receptor 5-Htr1b (p Conclusions Our results provide additional information on the role of LRP5 mutations and their

  4. Appropriate Crypt Formation in the Uterus for Embryo Homing and Implantation Requires Wnt5a-ROR Signaling

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    Jeeyeon Cha

    2014-07-01

    Full Text Available Embryo homing and implantation occur within a crypt (implantation chamber at the antimesometrial (AM pole along the uterus. The mechanism by which this is achieved is not known. Here, we show that villi-like epithelial projections from the main uterine lumen toward the AM pole at regularly spaced intervals that form crypts for embryo implantation were disrupted in mice with uterine loss or gain of function of Wnt5a, or loss of function of both Ror1 and Ror2. This disruption of Wnt5a-ROR signaling resulted in disorderly epithelial projections, crypt formation, embryo spacing, and impaired implantation. These early disturbances under abnormal Wnt5a-ROR signaling were reflected in adverse late pregnancy events, including defective decidualization and placentation, ultimately leading to compromised pregnancy outcomes. This study presents deeper insight regarding the formation of organized epithelial projections for crypt formation and embryo implantation for pregnancy success.

  5. Kinesin superfamily protein Kif26b links Wnt5a-Ror signaling to the control of cell and tissue behaviors in vertebrates.

    Science.gov (United States)

    Susman, Michael W; Karuna, Edith P; Kunz, Ryan C; Gujral, Taranjit S; Cantú, Andrea V; Choi, Shannon S; Jong, Brigette Y; Okada, Kyoko; Scales, Michael K; Hum, Jennie; Hu, Linda S; Kirschner, Marc W; Nishinakamura, Ryuichi; Yamada, Soichiro; Laird, Diana J; Jao, Li-En; Gygi, Steven P; Greenberg, Michael E; Ho, Hsin-Yi Henry

    2017-09-08

    Wnt5a-Ror signaling constitutes a developmental pathway crucial for embryonic tissue morphogenesis, reproduction and adult tissue regeneration, yet the molecular mechanisms by which the Wnt5a-Ror pathway mediates these processes are largely unknown. Using a proteomic screen, we identify the kinesin superfamily protein Kif26b as a downstream target of the Wnt5a-Ror pathway. Wnt5a-Ror, through a process independent of the canonical Wnt/β-catenin-dependent pathway, regulates the cellular stability of Kif26b by inducing its degradation via the ubiquitin-proteasome system. Through this mechanism, Kif26b modulates the migratory behavior of cultured mesenchymal cells in a Wnt5a-dependent manner. Genetic perturbation of Kif26b function in vivo caused embryonic axis malformations and depletion of primordial germ cells in the developing gonad, two phenotypes characteristic of disrupted Wnt5a-Ror signaling. These findings indicate that Kif26b links Wnt5a-Ror signaling to the control of morphogenetic cell and tissue behaviors in vertebrates and reveal a new role for regulated proteolysis in noncanonical Wnt5a-Ror signal transduction.

  6. Mathematical and Statistical Techniques for Systems Medicine: The Wnt Signaling Pathway as a Case Study

    KAUST Repository

    MacLean, Adam L.

    2015-12-16

    The last decade has seen an explosion in models that describe phenomena in systems medicine. Such models are especially useful for studying signaling pathways, such as the Wnt pathway. In this chapter we use the Wnt pathway to showcase current mathematical and statistical techniques that enable modelers to gain insight into (models of) gene regulation and generate testable predictions. We introduce a range of modeling frameworks, but focus on ordinary differential equation (ODE) models since they remain the most widely used approach in systems biology and medicine and continue to offer great potential. We present methods for the analysis of a single model, comprising applications of standard dynamical systems approaches such as nondimensionalization, steady state, asymptotic and sensitivity analysis, and more recent statistical and algebraic approaches to compare models with data. We present parameter estimation and model comparison techniques, focusing on Bayesian analysis and coplanarity via algebraic geometry. Our intention is that this (non-exhaustive) review may serve as a useful starting point for the analysis of models in systems medicine.

  7. Common genetic variants in Wnt signaling pathway genes as potential prognostic biomarkers for colorectal cancer.

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    Wen-Chien Ting

    Full Text Available Compelling evidence has implicated the Wnt signaling pathway in the pathogenesis of colorectal cancer. We assessed the use of tag single nucleotide polymorphisms (tSNPs in adenomatous polyposis coli (APC/β-catenin (CTNNB1 genes to predict outcomes in patients with colorectal cancer. We selected and genotyped 10 tSNP to predict common variants across entire APC and CTNNB1 genes in 282 colorectal cancer patients. The associations of these tSNPs with distant metastasis-free survival and overall survival were evaluated by Kaplan-Meier analysis, Cox regression model, and survival tree analysis. The 5-year overall survival rate was 68.3%. Survival tree analysis identified a higher-order genetic interaction profile consisting of the APC rs565453, CTNNB1 2293303, and APC rs1816769 that was significantly associated with overall survival. The 5-year survival overall rates were 89.2%, 66.1%, and 58.8% for the low-, medium-, and high-risk genetic profiles, respectively (log-rank P = 0.001. After adjusting for possible confounders, including age, gender, carcinoembryonic antigen levels, tumor differentiation, stage, lymphovascular invasion, perineural invasion, and lymph node involvement, the genetic interaction profile remained significant. None of the studied SNPs were individually associated with distant metastasis-free survival and overall survival. Our results suggest that the genetic interaction profile among Wnt pathway SNPs might potentially increase the prognostic value in outcome prediction for colorectal cancer.

  8. Niclosamide-conjugated polypeptide nanoparticles inhibit Wnt signaling and colon cancer growth.

    Science.gov (United States)

    Bhattacharyya, Jayanta; Ren, Xiu-Rong; Mook, Robert A; Wang, Jiangbo; Spasojevic, Ivan; Premont, Richard T; Li, Xinghai; Chilkoti, Ashutosh; Chen, Wei

    2017-08-31

    Abnormal Wnt activity is a major mechanism responsible for many diseases, including cancer. Previously, we reported that the anthelmintic drug Niclosamide (NIC) inhibits Wnt/β-catenin signaling and suppresses colon cancer cell growth. Although the pharmacokinetic properties of NIC are appropriate for use as an anthelmintic agent, its low solubility, low bioavailability and low systemic exposure limit its usefulness in treating systemic diseases. To overcome these limitations, we conjugated NIC to recombinant chimeric polypeptides (CPs), and the CP-NIC conjugate spontaneously self-assembled into sub-100 nm near-monodisperse nanoparticles. CP-NIC nanoparticles delivered intravenously act as a pro-drug of NIC to dramatically increase exposure of NIC compared to dosing with free NIC. CP-NIC improved anti-tumor activity compared to NIC in a xenograft model of human colon cancer. Because NIC has multiple biological activities, CP-NIC could be used for treatment of multiple diseases, including cancer, bacterial and viral infection, type II diabetes, NASH and NAFLD.

  9. MicroRNA-184 modulates canonical Wnt signaling through the regulation of frizzled-7 expression in the retina with ischemia-induced neovascularization.

    Science.gov (United States)

    Takahashi, Yusuke; Chen, Qian; Rajala, Raju V S; Ma, Jian-Xing

    2015-04-28

    Aberrant activation of Wnt signaling contributes to ischemia-induced retinal neovascularization in oxygen-induced retinopathy (OIR), although the underlying mechanism is so far unclear. Here, we show that microRNA-184 (miR-184) is significantly down-regulated in the retina of OIR mice, and miR-184 negatively modulates Wnt signaling both in vivo and in vitro. Furthermore, we show that the Wnt receptor, frizzled-7, is a downstream target of miR-184, and delivery of miR-184 mimic inhibits Wnt signaling in the OIR retina. These results suggest that decreased levels of miR-184 are responsible, at least in part, for the aberrant activation of Wnt signaling in ischemia-induced retinal neovascularization. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. Expression patterns of Wnt signaling component, secreted frizzled‑related protein 3 in astrocytoma and glioblastoma.

    Science.gov (United States)

    Pećina-Šlaus, Nives; Kafka, Anja; Varošanec, Ana Maria; Marković, Leon; Krsnik, Željka; Njirić, Niko; Mrak, Goran

    2016-05-01

    Secreted frizzled-related protein 3 (SFRP3) is a member of the family of soluble proteins, which modulate the Wnt signaling cascade. Novel research has identified aberrant expression of SFRPs in different types of cancer. In the present study the expression intensities and localizations of the SFRP3 protein across different histopathological grades of astrocytic brain tumors were investigated by immunohistochemistry, digital scanning and image analysis. The results demonstrated that the differences between expression levels and malignancy grades were statistically significant. Tumors were classified into four malignancy grades according to the World Health Organization guidelines. Moderate (P=0.014) and strong (P=0.028) nuclear expression levels were significantly different in pilocytic (grade I) and diffuse (grade II) astrocytomas demonstrating higher expression values, as compared with anaplastic astrocytoma (grade III) and glioblastoma (grade IV). When the sample was divided into two groups, the moderate and high cytoplasmic expression levels were observed to be significantly higher in glioblastomas than in the group comprising astrocytoma II and III. Furthermore, the results indicated that high grade tumors were associated with lower values of moderate (P=0.002) and strong (P=0.018) nuclear expression in comparison to low grade tumors. Analysis of cytoplasmic staining demonstrated that strong cytoplasmic expression was significantly higher in the astrocytoma III and IV group than in the astrocytoma I and II group (P=0.048). Furthermore, lower grade astrocytomas exhibited reduced membranous SFRP3 staining when compared with higher grade astrocytomas and this difference was statistically significant (P=0.036). The present results demonstrated that SFRP3 protein expression levels were decreased in the nucleus in higher grade astrocytoma (indicating the expected behavior of an antagonist of Wnt signaling), whereas when the SFRP3 was located in the

  11. Expression patterns of Wnt signaling component, secreted frizzled-related protein 3 in astrocytoma and glioblastoma

    Science.gov (United States)

    PEĆINA-ŠLAUS, NIVES; KAFKA, ANJA; VAROŠANEC, ANA MARIA; MARKOVIĆ, LEON; KRSNIK, ŽELJKA; NJIRIĆ, NIKO; MRAK, GORAN

    2016-01-01

    Secreted frizzled-related protein 3 (SFRP3) is a member of the family of soluble proteins, which modulate the Wnt signaling cascade. Novel research has identified aberrant expression of SFRPs in different types of cancer. In the present study the expression intensities and localizations of the SFRP3 protein across different histopathological grades of astrocytic brain tumors were investigated by immunohistochemistry, digital scanning and image analysis. The results demonstrated that the differences between expression levels and malignancy grades were statistically significant. Tumors were classified into four malignancy grades according to the World Health Organization guidelines. Moderate (P=0.014) and strong (P=0.028) nuclear expression levels were significantly different in pilocytic (grade I) and diffuse (grade II) astrocytomas demonstrating higher expression values, as compared with anaplastic astrocytoma (grade III) and glioblastoma (grade IV). When the sample was divided into two groups, the moderate and high cytoplasmic expression levels were observed to be significantly higher in glioblastomas than in the group comprising astrocytoma II and III. Furthermore, the results indicated that high grade tumors were associated with lower values of moderate (P=0.002) and strong (P=0.018) nuclear expression in comparison to low grade tumors. Analysis of cytoplasmic staining demonstrated that strong cytoplasmic expression was significantly higher in the astrocytoma III and IV group than in the astrocytoma I and II group (P=0.048). Furthermore, lower grade astrocytomas exhibited reduced membranous SFRP3 staining when compared with higher grade astrocytomas and this difference was statistically significant (P=0.036). The present results demonstrated that SFRP3 protein expression levels were decreased in the nucleus in higher grade astrocytoma (indicating the expected behavior of an antagonist of Wnt signaling), whereas when the SFRP3 was located in the cytoplasm an

  12. Inhibition of fibroblast growth by Notch1 signaling is mediated by induction of Wnt11-dependent WISP-1.

    Science.gov (United States)

    Liu, Zhao-Jun; Li, Yan; Tan, Yurong; Xiao, Min; Zhang, Jialin; Radtke, Freddy; Velazquez, Omaida C

    2012-01-01

    Fibroblasts are an integral component of stroma and important source of growth factors and extracellular matrix (ECM). They play a prominent role in maintaining tissue homeostasis and in wound healing and tumor growth. Notch signaling regulates biological function in a variety of cells. To elucidate the physiological function of Notch signaling in fibroblasts, we ablated Notch1 in mouse (Notch1(Flox/Flox)) embryonic fibroblasts (MEFs). Notch1-deficient (Notch1(-/-)) MEFs displayed faster growth and motility rate compared to Notch1(Flox/Flox) MEFs. Such phenotypic changes, however, were reversible by reconstitution of Notch1 activation via overexpression of the intracellular domain of Notch1 (NICD1) in Notch1-deficient MEFs. In contrast, constitutive activation of Notch1 signaling by introducing NICD1 into primary human dermal fibroblasts (FF2441), which caused pan-Notch activation, inhibited cell growth and motility, whereas cellular inhibition was relievable when the Notch activation was countered with dominant-negative mutant of Master-mind like 1 (DN-MAML-1). Functionally, "Notch-activated" stromal fibroblasts could inhibit tumor cell growth/invasion. Moreover, Notch activation induced expression of Wnt-induced secreted proteins-1 (WISP-1/CCN4) in FF2441 cells while deletion of Notch1 in MEFs resulted in an opposite effect. Notably, WISP-1 suppressed fibroblast proliferation, and was responsible for mediating Notch1's inhibitory effect since siRNA-mediated blockade of WISP-1 expression could relieve cell growth inhibition. Notch1-induced WISP-1 expression appeared to be Wnt11-dependent, but Wnt1-independent. Blockade of Wnt11 expression resulted in decreased WISP-1 expression and liberated Notch-induced cell growth inhibition. These findings indicated that inhibition of fibroblast proliferation by Notch pathway activation is mediated, at least in part, through regulating Wnt1-independent, but Wnt11-dependent WISP-1 expression.

  13. Inhibition of fibroblast growth by Notch1 signaling is mediated by induction of Wnt11-dependent WISP-1.

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    Zhao-Jun Liu

    Full Text Available Fibroblasts are an integral component of stroma and important source of growth factors and extracellular matrix (ECM. They play a prominent role in maintaining tissue homeostasis and in wound healing and tumor growth. Notch signaling regulates biological function in a variety of cells. To elucidate the physiological function of Notch signaling in fibroblasts, we ablated Notch1 in mouse (Notch1(Flox/Flox embryonic fibroblasts (MEFs. Notch1-deficient (Notch1(-/- MEFs displayed faster growth and motility rate compared to Notch1(Flox/Flox MEFs. Such phenotypic changes, however, were reversible by reconstitution of Notch1 activation via overexpression of the intracellular domain of Notch1 (NICD1 in Notch1-deficient MEFs. In contrast, constitutive activation of Notch1 signaling by introducing NICD1 into primary human dermal fibroblasts (FF2441, which caused pan-Notch activation, inhibited cell growth and motility, whereas cellular inhibition was relievable when the Notch activation was countered with dominant-negative mutant of Master-mind like 1 (DN-MAML-1. Functionally, "Notch-activated" stromal fibroblasts could inhibit tumor cell growth/invasion. Moreover, Notch activation induced expression of Wnt-induced secreted proteins-1 (WISP-1/CCN4 in FF2441 cells while deletion of Notch1 in MEFs resulted in an opposite effect. Notably, WISP-1 suppressed fibroblast proliferation, and was responsible for mediating Notch1's inhibitory effect since siRNA-mediated blockade of WISP-1 expression could relieve cell growth inhibition. Notch1-induced WISP-1 expression appeared to be Wnt11-dependent, but Wnt1-independent. Blockade of Wnt11 expression resulted in decreased WISP-1 expression and liberated Notch-induced cell growth inhibition. These findings indicated that inhibition of fibroblast proliferation by Notch pathway activation is mediated, at least in part, through regulating Wnt1-independent, but Wnt11-dependent WISP-1 expression.

  14. Structure-function analysis of the C-clamp of TCF/Pangolin in Wnt/ß-catenin signaling.

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    Aditi J Ravindranath

    Full Text Available The evolutionarily conserved Wnt/ß-catenin (Wnt/ß-cat pathway plays an important role in animal development in metazoans. Many Wnt targets are regulated by members of the TCF/LEF1 (TCF family of transcription factors. All TCFs contain a High Mobility Group (HMG domain that bind specific DNA sequences. Invertebrate TCFs and some vertebrate TCF isoforms also contain another domain, called the C-clamp, which allows TCFs to recognize an additional DNA motif known as the Helper site. While the C-clamp has been shown to be important for regulating several Wnt reporter genes in cell culture, its physiological role in regulating Wnt targets is less clear. In addition, little is known about this domain, except that two of the four conserved cysteines are functionally important. Here, we carried out a systematic mutagenesis and functional analysis of the C-clamp from the Drosophila TCF/Pangolin (TCF/Pan protein. We found that the C-clamp is a zinc-binding domain that is sufficient for binding to the Helper site. In addition to this DNA-binding activity, the C-clamp also inhibits the HMG domain from binding its cognate DNA site. Point mutations were identified that specifically affected DNA-binding or reduced the inhibitory effect. These mutants were characterized in TCF/Pan rescue assays. The specific DNA-binding activity of the C-clamp was essential for TCF/Pan function in cell culture and in patterning the embryonic epidermis of Drosophila, demonstrating the importance of this C-clamp activity in regulating Wnt target gene expression. In contrast, the inhibitory mutation had a subtle effect in cell culture and no effect on TCF/Pan activity in embryos. These results provide important information about the functional domains of the C-clamp, and highlight its importance for Wnt/ß-cat signaling in Drosophila.

  15. Structure-function analysis of the C-clamp of TCF/Pangolin in Wnt/ß-catenin signaling.

    Science.gov (United States)

    Ravindranath, Aditi J; Ravindranath, Aditi; Cadigan, Ken M

    2014-01-01

    The evolutionarily conserved Wnt/ß-catenin (Wnt/ß-cat) pathway plays an important role in animal development in metazoans. Many Wnt targets are regulated by members of the TCF/LEF1 (TCF) family of transcription factors. All TCFs contain a High Mobility Group (HMG) domain that bind specific DNA sequences. Invertebrate TCFs and some vertebrate TCF isoforms also contain another domain, called the C-clamp, which allows TCFs to recognize an additional DNA motif known as the Helper site. While the C-clamp has been shown to be important for regulating several Wnt reporter genes in cell culture, its physiological role in regulating Wnt targets is less clear. In addition, little is known about this domain, except that two of the four conserved cysteines are functionally important. Here, we carried out a systematic mutagenesis and functional analysis of the C-clamp from the Drosophila TCF/Pangolin (TCF/Pan) protein. We found that the C-clamp is a zinc-binding domain that is sufficient for binding to the Helper site. In addition to this DNA-binding activity, the C-clamp also inhibits the HMG domain from binding its cognate DNA site. Point mutations were identified that specifically affected DNA-binding or reduced the inhibitory effect. These mutants were characterized in TCF/Pan rescue assays. The specific DNA-binding activity of the C-clamp was essential for TCF/Pan function in cell culture and in patterning the embryonic epidermis of Drosophila, demonstrating the importance of this C-clamp activity in regulating Wnt target gene expression. In contrast, the inhibitory mutation had a subtle effect in cell culture and no effect on TCF/Pan activity in embryos. These results provide important information about the functional domains of the C-clamp, and highlight its importance for Wnt/ß-cat signaling in Drosophila.

  16. Heterotrimeric G protein-dependent WNT-5A signaling to ERK1/2 mediates distinct aspects of microglia proinflammatory transformation

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    Halleskog Carina

    2012-05-01

    Full Text Available Abstract Background WNT-5A signaling in the central nervous system is important for morphogenesis, neurogenesis and establishment of functional connectivity; the source of WNT-5A and its importance for cellular communication in the adult brain, however, are mainly unknown. We have previously investigated the inflammatory effects of WNT/β-catenin signaling in microglia in Alzheimer's disease. WNT-5A, however, generally recruits β-catenin-independent signaling. Thus, we aim here to characterize the role of WNT-5A and downstream signaling pathways for the inflammatory transformation of the brain's macrophages, the microglia. Methods Mouse brain sections were used for immunohistochemistry. Primary isolated microglia and astrocytes were employed to characterize the WNT-induced inflammatory transformation and underlying intracellular signaling pathways by immunoblotting, quantitative mRNA analysis, proliferation and invasion assays. Further, measurements of G protein activation by [γ-35 S]GTP binding, examination of calcium fluxes and cyclic AMP production were used to define intracellular signaling pathways. Results Astrocytes in the adult mouse brain express high levels of WNT-5A, which could serve as a novel astroglia-microglia communication pathway. The WNT-5A-induced proinflammatory microglia response is characterized by increased expression of inducible nitric oxide synthase, cyclooxygenase-2, cytokines, chemokines, enhanced invasive capacity and proliferation. Mapping of intracellular transduction pathways reveals that WNT-5A activates heterotrimeric Gi/o proteins to reduce cyclic AMP levels and to activate a Gi/o protein/phospholipase C/calcium-dependent protein kinase/extracellular signal-regulated kinase 1/2 (ERK1/2 axis. We show further that WNT-5A-induced ERK1/2 signaling is responsible for distinct aspects of the proinflammatory transformation, such as matrix metalloprotease 9/13 expression, invasion and proliferation. Conclusions

  17. The Tumor Suppressor Smad4/DPC4 Is Regulated by Phosphorylations that Integrate FGF, Wnt, and TGF-β Signaling

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    Hadrien Demagny

    2014-10-01

    Full Text Available Smad4 is a major tumor suppressor currently thought to function constitutively in the transforming growth factor β (TGF-β-signaling pathway. Here, we report that Smad4 activity is directly regulated by the Wnt and fibroblast growth factor (FGF pathways through GSK3 and mitogen-activated protein kinase (MAPK phosphorylation sites. FGF activates MAPK, which primes three sequential GSK3 phosphorylations that generate a Wnt-regulated phosphodegron bound by the ubiquitin E3 ligase β-TrCP. In the presence of FGF, Wnt potentiates TGF-β signaling by preventing Smad4 GSK3 phosphorylations that inhibit a transcriptional activation domain located in the linker region. When MAPK is not activated, the Wnt and TGF-β signaling pathways remain insulated from each other. In Xenopus embryos, these Smad4 phosphorylations regulate germ-layer specification and Spemann organizer formation. The results show that three major signaling pathways critical in development and cancer are integrated at the level of Smad4.

  18. Neuroprotective effect of rapamycin on spinal cord injury via activation of the Wnt/β-catenin signaling pathway

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    Kai Gao

    2015-01-01

    Full Text Available The Wnt/β-catenin signaling pathway plays a crucial role in neural development, axonal guidance, neuropathic pain remission and neuronal survival. In this study, we initially examined the effect of rapamycin on the Wnt/β-catenin signaling pathway after spinal cord injury, by intraperitoneally injecting spinal cord injured rats with rapamycin over 2 days. Western blot analysis and immunofluorescence staining were used to detect the expression levels of β-catenin protein, ca-spase-3 protein and brain-derived neurotrophic factor protein, components of the Wnt/β-catenin signaling pathway. Rapamycin increased the levels of β-catenin and brain-derived neurotrophic factor in the injured spinal cord, improved the pathological morphology at the injury site, reduced the loss of motor neurons, and promoted motor functional recovery in rats after spinal cord injury. Our experimental findings suggest that the neuroprotective effect of rapamycin intervention is mediated through activation of the Wnt/β-catenin signaling pathway after spinal cord injury.

  19. Characterisation of the liver progenitor cell niche in liver diseases: potential involvement of Wnt and Notch signalling

    NARCIS (Netherlands)

    Spee, B.|info:eu-repo/dai/nl/304830925; Carpino, G.; Schotanus, B.A.|info:eu-repo/dai/nl/304836524; Katoonizadeh, A.; Vander Borght, S.; Gaudio, E.; Roskams, T.

    2010-01-01

    Hepatology Characterisation of the liver progenitor cell niche in liver diseases: potential involvement of Wnt and Notch signalling Bart Spee1, Guido Carpino2, Baukje A Schotanus3, Azeam Katoonizadeh1, Sara Vander Borght1, Eugenio Gaudio4, Tania Roskams1 + Author Affiliations 1Department of

  20. Molecular cloning, characterization and expression analysis of Wnt4, Wnt5, Wnt6, Wnt7, Wnt10 and Wnt16 from Litopenaeus vannamei.

    Science.gov (United States)

    Zhang, Shuang; Li, Chao-Zheng; Yang, Qi-Hui; Dong, Xiao-Hui; Chi, Shu-Yan; Liu, Hong-Yu; Shi, Li-Li; Tan, Bei-Ping

    2016-07-01

    The Wnt (Wg-type MMTV integration site) signaling represents as the negative regulator of virus-induced innate immune responses. Wnt genes act as ligands to activate the Wnt signaling. To know more about the information of Wnt genes in invertebrates, Litopenaeus vannamei Wnt genes (LvWnts) were identified and characterized. In this study, Six Wnt genes (LvWnt4, LvWnt5, LvWnt6, LvWnt7, LvWnt10 and LvWnt16) were obtained in L. vannamei. The complete cDNAs open reading frames (ORF) of LvWnt4, LvWnt5, LvWnt6, LvWnt7, LvWnt10 and LvWnt16 were 1077 bp, 1107 bp, 1350 bp, 1047 bp, 1509 bp and 1158 bp (GenBank accession no. KU169896, KU169897, KU169898, KU169899, KU169900 and KU169901), encoding 358, 368, 449, 348, 502 and 385 amino acid (aa) residues respectively. All the six members of LvWnts contain a Wnt1 domain, which is considered as an important feature of Wnt gene family. ClustalW analysis with amino acid sequences revealed that the proportion of identity with other species was more than 48% for all the LvWnts except LvWnt10 (36-41%). The phylogenetic relationship analysis illustrated that different subtype of Wnts formed their own separate branches and were placed in branch of invertebrates respectively with strong bootstrap support. The constitutive expressions of LvWnts were confirmed by RT-PCR in all the examined five developmental stages and eleven tissues of L. vannamei with different express patterns. LvWnt4, LvWnt5 and LvWnt10 were expressed highest in nerve while LvWnt6, LvWnt7 and LvWnt16 were expressed highest in intestine, stomach and gill, respectively. In addition, all the LvWnts were regulated by white spot syndrome virus (WSSV) challenges at different levels in hepatopancreas, gill and hemocytes, suggesting that Wnt genes may play a role in the defense against pathogenic virus infection in innate immune of L. vannamei. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Anti-Sclerostin antibody inhibits internalization of Sclerostin and Sclerostin-mediated antagonism of Wnt/LRP6 signaling.

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    Maarten van Dinther

    Full Text Available Sclerosteosis is a rare high bone mass disease that is caused by inactivating mutations in the SOST gene. Its gene product, Sclerostin, is a key negative regulator of bone formation and might therefore serve as a target for the anabolic treatment of osteoporosis. The exact molecular mechanism by which Sclerostin exerts its antagonistic effects on Wnt signaling in bone forming osteoblasts remains unclear. Here we show that Wnt3a-induced transcriptional responses and induction of alkaline phosphatase activity, an early marker of osteoblast differentiation, require the Wnt co-receptors LRP5 and LRP6. Unlike Dickkopf1 (DKK1, Sclerostin does not inhibit Wnt-3a-induced phosphorylation of LRP5 at serine 1503 or LRP6 at serine 1490. Affinity labeling of cell surface proteins with [(125I]Sclerostin identified LRP6 as the main specific Sclerostin receptor in multiple mesenchymal cell lines. When cells were challenged with Sclerostin fused to recombinant green fluorescent protein (GFP this was internalized, likely via a Clathrin-dependent process, and subsequently degraded in a temperature and proteasome-dependent manner. Ectopic expression of LRP6 greatly enhanced binding and cellular uptake of Sclerostin-GFP, which was reduced by the addition of an excess of non-GFP-fused Sclerostin. Finally, an anti-Sclerostin antibody inhibited the internalization of Sclerostin-GFP and binding of Sclerostin to LRP6. Moreover, this antibody attenuated the antagonistic activity of Sclerostin on canonical Wnt-induced responses.

  2. Signalling through the Type 1 Insulin-Like Growth Factor Receptor (IGF1R Interacts with Canonical Wnt Signalling to Promote Neural Proliferation in Developing Brain

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    Qichen Hu

    2012-05-01

    Full Text Available Signalling through the IGF1R [type 1 IGF (insulin-like growth factor receptor] and canonical Wnt signalling are two signalling pathways that play critical roles in regulating neural cell generation and growth. To determine whether the signalling through the IGF1R can interact with the canonical Wnt signalling pathway in neural cells in vivo, we studied mutant mice with altered IGF signalling. We found that in mice with blunted IGF1R expression specifically in nestin-expressing neural cells (IGF1RNestin–KO mice the abundance of neural β-catenin was significantly reduced. Blunting IGF1R expression also markedly decreased: (i the activity of a LacZ (β-galactosidase reporter transgene that responds to Wnt nuclear signalling (LacZTCF reporter transgene and (ii the number of proliferating neural precursors. In contrast, overexpressing IGF-I (insulin-like growth factor I in brain markedly increased the activity of the LacZTCF reporter transgene. Consistently, IGF-I treatment also markedly increased the activity of the LacZTCF reporter transgene in embryonic neuron cultures that are derived from LacZTCF Tg (transgenic mice. Importantly, increasing the abundance of β-catenin in IGF1RNestin–KO embryonic brains by suppressing the activity of GSK3β (glycogen synthase kinase-3β significantly alleviated the phenotypic changes induced by IGF1R deficiency. These phenotypic changes includes: (i retarded brain growth, (ii reduced precursor proliferation and (iii decreased neuronal number. Our current data, consistent with our previous study of cultured oligodendrocytes, strongly support the concept that IGF signalling interacts with canonical Wnt signalling in the developing brain to promote neural proliferation. The interaction of IGF and canonical Wnt signalling plays an important role in normal brain development by promoting neural precursor proliferation.

  3. Hairless controls hair fate decision via Wnt/β-catenin signaling.

    Science.gov (United States)

    Zhu, Kuicheng; Xu, Cunshuan; Liu, Mengduan; Zhang, Jintao

    2017-09-23

    The hairless (Hr) gene plays a central role in the hair cycle, considering that mutations in the gene result in hair loss with the exception of a few vibrissae after the first hair growth cycle in both mice and humans. This study examinedthe uncommon phenotype and using microarray analyses and functional studies, we found that β-catenin was mediated by Hr. Progenitor keratinocytes from the bulge region differentiate into both epidermis and sebaceous glands, and fail to adopt the hair keratinocytes fate in the mutant scalp, due to the decreased Wnt/β-catenin signaling in the absence of the hairless protein. This may be attributed to the dysfunction of normal epithelial-mesenchymal interactions in the hair follicle (HF). Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Modular and Stochastic Approaches to Molecular Pathway Models of ATM, TGF beta, and WNT Signaling

    Science.gov (United States)

    Cucinotta, Francis A.; O'Neill, Peter; Ponomarev, Artem; Carra, Claudio; Whalen, Mary; Pluth, Janice M.

    2009-01-01

    Deterministic pathway models that describe the biochemical interactions of a group of related proteins, their complexes, activation through kinase, etc. are often the basis for many systems biology models. Low dose radiation effects present a unique set of challenges to these models including the importance of stochastic effects due to the nature of radiation tracks and small number of molecules activated, and the search for infrequent events that contribute to cancer risks. We have been studying models of the ATM, TGF -Smad and WNT signaling pathways with the goal of applying pathway models to the investigation of low dose radiation cancer risks. Modeling challenges include introduction of stochastic models of radiation tracks, their relationships to more than one substrate species that perturb pathways, and the identification of a representative set of enzymes that act on the dominant substrates. Because several pathways are activated concurrently by radiation the development of modular pathway approach is of interest.

  5. Kirenol inhibits adipogenesis through activation of the Wnt/β-catenin signaling pathway in 3T3-L1 adipocytes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi-Bo [Department of Biomaterials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Song, Youngwoo; Kim, Changhee [Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Hwang, Jae-Kwan, E-mail: jkhwang@yonsei.ac.kr [Department of Biomaterials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2014-03-07

    Highlights: • Kirenol inhibits the adipogenic transcription factors and lipogenic enzymes. • Kirenol stimulates the Wnt/β-catenin signaling pathway components. • Kirenol inhibits adipogenesis through activation of the Wnt/β-catenin signaling pathway. - Abstract: Kirenol, a natural diterpenoid compound, has been reported to possess anti-oxidant, anti-inflammatory, anti-allergic, and anti-arthritic activities; however, its anti-adipogenic effect remains to be studied. The present study evaluated the effect of kirenol on anti-adipogenesis through the activation of the Wnt/β-catenin signaling pathway. Kirenol prevented intracellular lipid accumulation by down-regulating key adipogenesis transcription factors [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding proteins α (C/EBPα), and sterol regulatory element binding protein-1c (SREBP-1c)] and lipid biosynthesis-related enzymes [fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC)], as well as adipocytokines (adiponectin and leptin). Kirenol effectively activated the Wnt/β-catenin signaling pathway, in which kirenol up-regulated the expression of low density lipoprotein receptor related protein 6 (LRP6), disheveled 2 (DVL2), β-catenin, and cyclin D1 (CCND1), while it inactivated glycogen synthase kinase 3β (GSK3β) by increasing its phosphorylation. Kirenol down-regulated the expression levels of PPARγ and C/EBPα, which were up-regulated by siRNA knockdown of β-catenin. Overall, kirenol is capable of inhibiting the differentiation and lipogenesis of 3T3-L1 adipocytes through the activation of the Wnt/β-catenin signaling pathway, suggesting its potential as natural anti-obesity agent.

  6. Cryptosporidium parvum-induced ileo-caecal adenocarcinoma and Wnt signaling in a mouse model

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    Sadia Benamrouz

    2014-06-01

    Full Text Available Cryptosporidium species are apicomplexan protozoans that are found worldwide. These parasites constitute a large risk to human and animal health. They cause self-limited diarrhea in immunocompetent hosts and a life-threatening disease in immunocompromised hosts. Interestingly, Cryptosporidium parvum has been related to digestive carcinogenesis in humans. Consistent with a potential tumorigenic role of this parasite, in an original reproducible animal model of chronic cryptosporidiosis based on dexamethasone-treated or untreated adult SCID mice, we formerly reported that C. parvum (strains of animal and human origin is able to induce digestive adenocarcinoma even in infections induced with very low inoculum. The aim of this study was to further characterize this animal model and to explore metabolic pathways potentially involved in the development of C. parvum-induced ileo-caecal oncogenesis. We searched for alterations in genes or proteins commonly involved in cell cycle, differentiation or cell migration, such as β-catenin, Apc, E-cadherin, Kras and p53. After infection of animals with C. parvum we demonstrated immunohistochemical abnormal localization of Wnt signaling pathway components and p53. Mutations in the selected loci of studied genes were not found after high-throughput sequencing. Furthermore, alterations in the ultrastructure of adherens junctions of the ileo-caecal neoplastic epithelia of C. parvum-infected mice were recorded using transmission electron microscopy. In conclusion, we found for the first time that the Wnt signaling pathway, and particularly the cytoskeleton network, seems to be pivotal for the development of the C. parvum-induced neoplastic process and cell migration of transformed cells. Furthermore, this model is a valuable tool in understanding the host-pathogen interactions associated with the intricate infection process of this parasite, which is able to modulate host cytoskeleton activities and several host

  7. Fibulin-4 reduces extracellular matrix production and suppresses chondrocyte differentiation via DKK1- mediated canonical Wnt/β-catenin signaling.

    Science.gov (United States)

    Shangguan, Lei; Ning, Guangzhi; Luo, Zhuojing; Zhou, Yue

    2017-06-01

    Fibulin-4 is an extracellular matrix (ECM) protein implicated in connective tissue development and elastic fiber formation. However, little is known about the underlying function of Fibulin-4 in cartilage development. The aim of this study was to investigate the role and probable mechanism of Fibulin-4 stimulation in ECM production and chondrocyte differentiation. Fibulin-4 has been observed to be abnormally elevated and matrix metalloproteinases 13 (MMP13) level was highly expressed in human osteoarthritis (OA) chondrocytes. In the chondrogenic cell line ATDC5, Fibulin-4 stimulation profoundly inhibited the expression of ECM gene type II collagen (Col2a1), aggrecan (Acan), and type X collagen (Col10a1). Overexpression of Fibulin-4 attenuated the expression of master transcription factors Sox6, Sox9 and Runx2, but had no effect on the expression of Sox5. Additionally, Fibulin-4 stimulation activated canonical Wnt pathway by reducing the expression of Wnt inhibitor DKK1 but not Sost. Moreover, Fibulin-4 augmented the expression of Wnt/β-catenin signaling target genes like β-catenin and Wnt-3a as well as diminished GSK-3β activation, and DKK1 abolished the effect of Fibulin-4 on chondrocyte differentiation, suggesting that Fibulin-4 is an important regulator of ECM production and chondrocyte differentiation through DKK1-mediated Wnt/β-catenin signaling. Our study provides evidence of a previously unknown link between Fibulin-4 and the canonical Wnt/β-catenin pathway that may contribute to our understanding of the molecular mechanisms of OA. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. [Canonical Wnt signaling pathway of the osteogenic differentiation of human periodontal ligament stem cells induced by advanced glycation end products].

    Science.gov (United States)

    Yan, Wu; Chao, Deng; Kun, Yang; Xiaoxia, Cui; Qi, Liu; Yan, Jin

    2015-12-01

    The effect of advanced glycation end products (AGEs) on the osteogenic differentiation of humanperiodontal ligament stem cells(hPDLSCs) was discussed. Changes in the Wnt signaling pathway during glycation were also determined. In vitro tissue explanting method was primarily applied. Limiting diluted clone was cultured to obtain hPDLSCs in vitro. The subjects were divided into two groups: the healthy group (N-hPDLSCs) and the AGEs-stimulating group (A-hPDLSCs). Osteoblast mineralization was induced in the experimental groups. The following processes were performed: alizarin red staining; alkaline phosphatase (ALP) staining; real time polymerase chain reaction (real time PCR) for detecting osteogenic genes and Wnt classical pathway-related factors, DKK-1 and β-catenin; Western blot analysis. Bone protein and β-catenin were correlated in the nuclear expression. The cells were osteogenically induced. ALP staining showed that the N-hPDLSCs displayed the deepest color. Alizarin red staining indicated that the A-hPDLSCs group had less calcified nodules than the N-hPDLSCs group. The real time PCR results suggested that the expression of relative osteogenic genes in A-hPDLSCs was quite low. Statistically significant differences in differentiation were found between groups (P < 0.05). The Western blot result was similar to that of real time PCR. Classical Wnt signaling pathway-related factor β-catenin was higher in A-hPDLSCs than in N-hPDLSCs. By contrast, DKK-1, which is an inhibitor in the Wnt pathway, had a significantly lower expression rate in A-hPDLSCs than in N-hPDLSCs. The Western blot result also showed that β-catenin expression in the nucleoprotein in A-hPDLSCs was notably higher than in N-hPDLSCs. AGEs can inhibit hPDLSCs osteogenic differentiation. AGEs induce changes in the normal periodontal ligament stem cells classical Wnt pathway. Canonical Wnt pathway is reactivated because of AGEs stimulation.

  9. A Wnt-planar polarity pathway instructs neurite branching by restricting F-actin assembly through endosomal signaling

    Science.gov (United States)

    Chen, Chun-Hao; Liao, Chien-Po

    2017-01-01

    Spatial arrangement of neurite branching is instructed by both attractive and repulsive cues. Here we show that in C. elegans, the Wnt family of secreted glycoproteins specify neurite branching sites in the PLM mechanosensory neurons. Wnts function through MIG-1/Frizzled and the planar cell polarity protein (PCP) VANG-1/Strabismus/Vangl2 to restrict the formation of F-actin patches, which mark branching sites in nascent neurites. We find that VANG-1 promotes Wnt signaling by facilitating Frizzled endocytosis and genetically acts in a common pathway with arr-1/β-arrestin, whose mutation results in defective PLM branching and F-actin patterns similar to those in the Wnt, mig-1 or vang-1 mutants. On the other hand, the UNC-6/Netrin pathway intersects orthogonally with Wnt-PCP signaling to guide PLM branch growth along the dorsal-ventral axis. Our study provides insights for how attractive and repulsive signals coordinate to sculpt neurite branching patterns, which are critical for circuit connectivity. PMID:28384160

  10. Arginine Enhances Osteoblastogenesis and Inhibits Adipogenesis through the Regulation of Wnt and NFATc Signaling in Human Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Jeong-Eun Huh

    2014-07-01

    Full Text Available Arginine, an α-amino acid, has been reported to exert beneficial effects that ameliorate health problems and prevent excessive fat deposition. In this study, we investigated whether the activation of cell signaling by arginine can induce osteogenic differentiation and modulate excessive adipogenic differentiation in human mesenchymal stem cells (MSCs. Arginine potently induced the expression of type Iα1 collagen, osteocalcin, and ALP in a dose-dependent manner without causing cytotoxicity. Arginine significantly increased the mRNA expression of the osteogenic transcription factors runt-related transcription factor 2 (Runx2, DIx5, and osterix. Furthermore, arginine demonstrated its antiadipogenicity by decreasing adipocyte formation and triglyceride (TG content in MSCs and inhibiting the mRNA expression of the adipogenic transcription factors peroxisome proliferator-activated receptor γ (PPARγ, CCAAT/enhancer-binding protein α (C/EBPα, and fatty acid binding protein 4 (Fabp4. This effect was associated with increased expression of Wnt5a, and nuclear factor of activated T-cells (NFATc, and was abrogated by antagonists of Wnt and NFATc, which indicated a role of Wnt and NFATc signaling in the switch from adipogenesis to osteoblastogenesis induced by arginine. In conclusion, this is the first report of the dual action of arginine in promoting osteogenesis and inhibiting adipocyte formation through involving Wnt5a and NFATc signaling pathway.

  11. Biphasic role of chondroitin sulfate in cardiac differentiation of embryonic stem cells through inhibition of Wnt/β-catenin signaling.

    Directory of Open Access Journals (Sweden)

    Robert D Prinz

    Full Text Available The glycosaminoglycan chondroitin sulfate is a critical component of proteoglycans on the cell surface and in the extracellular matrix. As such, chondroitin sulfate side chains and the sulfation balance of chondroitin play important roles in the control of signaling pathways, and have a functional importance in human disease. In contrast, very little is known about the roles of chondroitin sulfate molecules and sulfation patterns during mammalian development and cell lineage specification. Here, we report a novel biphasic role of chondroitin sulfate in the specification of the cardiac cell lineage during embryonic stem cell differentiation through modulation of Wnt/beta-catenin signaling. Lineage marker analysis demonstrates that enzymatic elimination of endogenous chondroitin sulfates leads to defects specifically in cardiac differentiation. This is accompanied by a reduction in the number of beating cardiac foci. Mechanistically, we show that endogenous chondroitin sulfate controls cardiac differentiation in a temporal biphasic manner through inhibition of the Wnt/beta-catenin pathway, a known regulatory pathway for the cardiac lineage. Treatment with a specific exogenous chondroitin sulfate, CS-E, could mimic these biphasic effects on cardiac differentiation and Wnt/beta-catenin signaling. These results establish chondroitin sulfate and its sulfation balance as important regulators of cardiac cell lineage decisions through control of the Wnt/beta-catenin pathway. Our work suggests that targeting the chondroitin biosynthesis and sulfation machinery is a novel promising avenue in regenerative strategies after heart injury.

  12. Evidence for involvement of Wnt signalling in body polarities, cell proliferation, and the neuro-sensory system in an adult ctenophore.

    Science.gov (United States)

    Jager, Muriel; Dayraud, Cyrielle; Mialot, Antoine; Quéinnec, Eric; le Guyader, Hervé; Manuel, Michaël

    2013-01-01

    Signalling through the Wnt family of secreted proteins originated in a common metazoan ancestor and greatly influenced the evolution of animal body plans. In bilaterians, Wnt signalling plays multiple fundamental roles during embryonic development and in adult tissues, notably in axial patterning, neural development and stem cell regulation. Studies in various cnidarian species have particularly highlighted the evolutionarily conserved role of the Wnt/β-catenin pathway in specification and patterning of the primary embryonic axis. However in another key non-bilaterian phylum, Ctenophora, Wnts are not involved in early establishment of the body axis during embryogenesis. We analysed the expression in the adult of the ctenophore Pleurobrachia pileus of 11 orthologues of Wnt signalling genes including all ctenophore Wnt ligands and Fz receptors and several members of the intracellular β-catenin pathway machinery. All genes are strongly expressed around the mouth margin at the oral pole, evoking the Wnt oral centre of cnidarians. This observation is consistent with primary axis polarisation by the Wnts being a universal metazoan feature, secondarily lost in ctenophores during early development but retained in the adult. In addition, local expression of Wnt signalling genes was seen in various anatomical structures of the body including in the locomotory comb rows, where their complex deployment suggests control by the Wnts of local comb polarity. Other important contexts of Wnt involvement which probably evolved before the ctenophore/cnidarian/bilaterian split include proliferating stem cells and progenitors irrespective of cell types, and developing as well as differentiated neuro-sensory structures.

  13. Reciprocal signaling by Wnt and Notch specifies a muscle precursor in the C. elegans embryo.

    Science.gov (United States)

    Robertson, Scott M; Medina, Jessica; Oldenbroek, Marieke; Lin, Rueyling

    2017-02-01

    The MS blastomere produces one-third of the body wall muscles (BWMs) in the C. elegans embryo. MS-derived BWMs require two distinct cell-cell interactions, the first inhibitory and the second, two cell cycles later, required to overcome this inhibition. The inductive interaction is not required if the inhibitory signal is absent. Although the Notch receptor GLP-1 was implicated in both interactions, the molecular nature of the two signals was unknown. We now show that zygotically expressed MOM-2 (Wnt) is responsible for both interactions. Both the inhibitory and the activating interactions require precise spatiotemporal expression of zygotic MOM-2, which is dependent upon two distinct Notch signals. In a Notch mutant defective only in the inductive interaction, MS-derived BWMs can be restored by preventing zygotic MOM-2 expression, which removes the inhibitory signal. Our results suggest that the inhibitory interaction ensures the differential lineage specification of MS and its sister blastomere, whereas the inductive interaction promotes the expression of muscle-specifying genes by modulating TCF and β-catenin levels. These results highlight the complexity of cell fate specification by cell-cell interactions in a rapidly dividing embryo. © 2017. Published by The Company of Biologists Ltd.

  14. Inhibition of melanogenesis by the pyridinyl imidazole class of compounds: possible involvement of the Wnt/β-catenin signaling pathway.

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    Barbara Bellei

    Full Text Available While investigating the role of p38 MAPK in regulating melanogenesis, we found that pyridinyl imidazole inhibitors class compounds as well as the analog compound SB202474, which does not inhibit p38 MAPK, suppressed both α-MSH-induced melanogenesis and spontaneous melanin synthesis. In this study, we demonstrated that the inhibitory activity of the pyridinyl imidazoles correlates with inhibition of the canonical Wnt/β-catenin pathway activity. Imidazole-treated cells showed a reduction in the level of Tcf/Lef target genes involved in the β-catenin signaling network, including ubiquitous genes such as Axin2, Lef1, and Wisp1 as well as cell lineage-restricted genes such as microphthalmia-associated transcription factor and dopachrome tautomerase. Although over-expression of the Wnt signaling pathway effector β-catenin slightly restored the melanogenic program, the lack of complete reversion suggested that the imidazoles interfered with β-catenin-dependent transcriptional activity rather than with β-catenin expression. Accordingly, we did not observe any significant change in β-catenin protein expression. The independence of p38 MAPK activity from the repression of Wnt/β-catenin signaling pathway was confirmed by small interfering RNA knockdown of p38 MAPK expression, which by contrast, stimulated β-catenin-driven gene expression. Our data demonstrate that the small molecule pyridinyl imidazoles possess two distinct and opposite mechanisms that modulate β-catenin dependent transcription: a p38 inhibition-dependent effect that stimulates the Wnt pathway by increasing β-catenin protein expression and an off-target mechanism that inhibits the pathway by repressing β-catenin protein functionality. The p38-independent effect seems to be dominant and, at least in B16-F0 cells, results in a strong block of the Wnt/β-catenin signaling pathway.

  15. Hematopoietic stem cell development requires transient Wnt/β-catenin activity

    NARCIS (Netherlands)

    C. Ruiz-Herguido (Cristina); J. Guiu (Jordi); C. D'Altri; J. Inglés-Esteve (Julia); E.A. Dzierzak (Elaine); L. Espinosa (Lluis); A. Bigas (Anna)

    2012-01-01

    textabstractUnderstanding how hematopoietic stem cells (HSCs) are generated and the signals that control this process is a crucial issue for regenerative medicine applications that require in vitro production of HSC. HSCs emerge during embryonic life from an endothelial-like cell population that

  16. A p38 Mitogen-Activated Protein Kinase-Regulated Myocyte Enhancer Factor 2–β-Catenin Interaction Enhances Canonical Wnt Signaling

    Science.gov (United States)

    Ehyai, Saviz; Dionyssiou, Mathew G.; Gordon, Joseph W.; Williams, Declan; Siu, K. W. Michael

    2015-01-01

    Canonical Wnt/β-catenin signaling plays a major role in various biological contexts, such as embryonic development, cell proliferation, and cancer progression. Previously, a connection between p38 mitogen-activated protein kinase (MAPK) signaling and Wnt-mediated activation of β-catenin was implied but poorly understood. In the present study, we investigated potential cross talk between p38 MAPK and Wnt/β-catenin signaling. Here we show that a loss of p38 MAPK α/β function reduces β-catenin nuclear accumulation in Wnt3a-stimulated primary vascular smooth muscle cells (VSMCs). Conversely, active p38 MAPK signaling increases β-catenin nuclear localization and target gene activity in multiple cell types. Furthermore, the effect of p38 MAPK α/β on β-catenin activity is mediated through phosphorylation of a key p38 MAPK target, myocyte enhancer factor 2 (MEF2). Here we report a p38 MAPK-mediated, phosphorylation-dependent interaction between MEF2 and β-catenin in multiple cell types and primary VSMCs that results in (i) increased β-catenin nuclear retention, which is reversed by small interfering RNA (siRNA)-mediated MEF2 gene silencing; (ii) increased activation of MEF2 and Wnt/β-catenin target genes; and (iii) increased Wnt-stimulated cell proliferation. These observations provide mechanistic insight into a fundamental level of cross talk between p38 MAPK/MEF2 signaling and canonical Wnt signaling. PMID:26552705

  17. Jarid2 Coordinates Nanog Expression and PCP/Wnt Signaling Required for Efficient ESC Differentiation and Early Embryo Development

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    David Landeira

    2015-07-01

    Full Text Available Jarid2 is part of the Polycomb Repressor complex 2 (PRC2 responsible for genome-wide H3K27me3 deposition. Unlike other PRC2-deficient embryonic stem cells (ESCs, however, Jarid2-deficient ESCs show a severe differentiation block, altered colony morphology, and distinctive patterns of deregulated gene expression. Here, we show that Jarid2−/− ESCs express constitutively high levels of Nanog but reduced PCP signaling components Wnt9a, Prickle1, and Fzd2 and lowered β-catenin activity. Depletion of Wnt9a/Prickle1/Fzd2 from wild-type ESCs or overexpression of Nanog largely phenocopies these cellular defects. Co-culture of Jarid2−/− with wild-type ESCs restores variable Nanog expression and β-catenin activity and can partially rescue the differentiation block of mutant cells. In addition, we show that ESCs lacking Jarid2 or Wnt9a/Prickle1/Fzd2 or overexpressing Nanog induce multiple ICM formation when injected into normal E3.5 blastocysts. These data describe a previously unrecognized role for Jarid2 in regulating a core pluripotency and Wnt/PCP signaling circuit that is important for ESC differentiation and for pre-implantation development.

  18. Involvement of Wnt signaling pathway in murine medulloblastoma induced by human neurotropic JC virus.

    Science.gov (United States)

    Gan, D D; Reiss, K; Carrill, T; Del Valle, L; Croul, S; Giordano, A; Fishman, P; Khalili, K

    2001-08-09

    By using the early genome of the human neurotropic polyomavirus, JCV, we have created transgenic animals that develop cerebellar primitive neuroectodermal tumors which model human medulloblastoma. Expression of T-antigen was found in some, but not all, tumor cells, and examination of the clonal cell lines derived from the tumor population showed enhanced tumorigenicity of cells expressing T-antigen in comparison to T-antigen negative cells. Considering the earlier notion on the potential involvement of beta-catenin with human medulloblastoma, we investigated various components of the Wnt signaling pathway including beta-catenin, its partner transcription factor, LEF-1, and their downstream target gene c-myc in these two cell populations. Immunohistochemical staining of the cells revealed enhanced nuclear appearance of beta-catenin in T-antigen positive cells. Results from Western blot showed higher levels of beta-catenin and LEF-1 in T-antigen positive cells in comparison to those in T-antigen negative cells. The enhanced level of LEF-1 expression correlated with the increase in DNA binding activity of this protein in nuclear extracts of T-antigen positive cells. Results from Northern and Western blot analyses revealed that the level of c-myc expression is augmented both at the RNA and protein levels in T-antigen positive cells. These observations corroborated results from transfection studies indicating the ability of JCV T-antigen to stimulate c-myc promoter activity. Further, co-transfection experiments revealed that the amount of c-myc and T-antigen protein in tumor cells may dictate the activity of JCV early promoter in these cells. These observations are interesting in light of recent discoveries on the association of JCV with human medulloblastoma and suggest that communication between JCV and the Wnt pathway may be an important event in the genesis of these tumors.

  19. Inhibition of Wnt/β-catenin signaling by dexamethasone promotes adipocyte differentiation in mesenchymal progenitor cells, ROB-C26.

    Science.gov (United States)

    Naito, Masako; Omoteyama, Kazuki; Mikami, Yoshikazu; Takahashi, Tomihisa; Takagi, Minoru

    2012-12-01

    Dexamethasone (Dex) stimulates the differentiation of mesenchymal progenitor cells into adipocytes and osteoblasts. However, the mechanisms underlying Dex-induced differentiation have not been clearly elucidated. We examined the effect of Dex on the expression and activity of Wnt/β-catenin signal-related molecules in a clonal mesenchymal progenitor cell line, ROB-C26 (C26). Dex induced the mRNA expression of Wnt antagonists, dickkopf-1 (Dkk-1), and Wnt inhibitory factor (WIF)-1. Immunocytochemical analysis showed that the downregulation of β-catenin protein expression by Dex occured concomitantly with the increased expression of the PPARγ protein. Dex decreased phosphorylation of Ser9-GSK3β and expression of active β-catenin protein. To examine the effects of Dex on Wnt/β-catenin activity, we used immunocytochemistry to analyze TCF/LEF-mediated transcription during Dex-induced adipogenesis in Wnt indicator (TOPEGFP) C26 cells. Our results demonstrated that Dex repressed TCF/LEF-mediated transcription, but induced adipocyte differentiation. Treatment with a GSK3β inhibitor attenuated Dex-induced inhibition of TCF/LEF-mediated transcriptional activity, but suppressed Dex-induced adipocyte differentiation, indicating that adipocyte differentiation and inhibition of Wnt/β-catenin activity by Dex are mediated by GSK3β activity. Furthermore, β-catenin knockdown not only suppressed Dex-induced ALP-positive osteoblasts differentiation but also promoted Dex-induced adipocytes differentiation. These results suggest that inhibition of β-catenin expression by Dex promotes the differentiation of mesenchymal progenitor cells into adipocytes.

  20. A20 restricts wnt signaling in intestinal epithelial cells and suppresses colon carcinogenesis.

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    Ling Shao

    Full Text Available Colon carcinogenesis consists of a multistep process during which a series of genetic and epigenetic adaptations occur that lead to malignant transformation. Here, we have studied the role of A20 (also known as TNFAIP3, a ubiquitin-editing enzyme that restricts NFκB and cell death signaling, in intestinal homeostasis and tumorigenesis. We have found that A20 expression is consistently reduced in human colonic adenomas than in normal colonic tissues. To further investigate A20's potential roles in regulating colon carcinogenesis, we have generated mice lacking A20 specifically in intestinal epithelial cells and interbred these with mice harboring a mutation in the adenomatous polyposis coli gene (APC(min. While A20(FL/FL villin-Cre mice exhibit uninflamed intestines without polyps, A20(FL/FL villin-Cre APC(min/+ mice contain far greater numbers and larger colonic polyps than control APC(min mice. We find that A20 binds to the β-catenin destruction complex and restricts canonical wnt signaling by supporting ubiquitination and degradation of β-catenin in intestinal epithelial cells. Moreover, acute deletion of A20 from intestinal epithelial cells in vivo leads to enhanced expression of the β-catenin dependent genes cyclinD1 and c-myc, known promoters of colon cancer. Taken together, these findings demonstrate new roles for A20 in restricting β-catenin signaling and preventing colon tumorigenesis.

  1. Sonic Hedgehog and WNT Signaling Promote Adrenal Gland Regeneration in Male Mice.

    Science.gov (United States)

    Finco, Isabella; Lerario, Antonio M; Hammer, Gary D

    2018-02-01

    The atrophy and hypofunction of the adrenal cortex following long-term pharmacologic glucocorticoid therapy is a major health problem necessitating chronic glucocorticoid replacement that often prolongs the ultimate return of endogenous adrenocortical function. Underlying this functional recovery is anatomic regeneration, the cellular and molecular mechanisms of which are poorly understood. Investigating the lineage contribution of cortical Sonic hedgehog (Shh)+ progenitor cells and the SHH-responsive capsular Gli1+ cells to the regenerating adrenal cortex, we observed a spatially and temporally bimodal contribution of both cell types to adrenocortical regeneration following cessation of glucocorticoid treatment. First, an early repopulation of the cortex is defined by a marked delamination and expansion of capsular Gli1+ cells, recapitulating the establishment of the capsular-cortical homeostatic niche during embryonic development. This rapid repopulation is promptly cleared from the cortical compartment only to be supplanted by repopulating cortical cells derived from the resident long-term-retained zona glomerulosa Shh+ progenitors. Pharmacologic and genetic dissection of SHH signaling further defines an SHH-dependent activation of WNT signaling that supports regeneration of the cortex following long-term glucocorticoid therapy. We define the signaling and lineage relationships that underlie the regeneration process. Copyright © 2018 Endocrine Society.

  2. Inorganic polyphosphate promotes cyclin D1 synthesis through activation of mTOR/Wnt/β-catenin signaling in endothelial cells.

    Science.gov (United States)

    Hassanian, S M; Ardeshirylajimi, A; Dinarvand, P; Rezaie, A R

    2016-11-01

    Essentials Polyphosphate (polyP) activates mTOR but its role in Wnt/β-catenin signaling is not known. PolyP-mediated cyclin D1 expression (β-catenin target gene) was monitored in endothelial cells. PolyP and boiled platelet-releasates induced the expression of cyclin D1 by similar mechanisms. PolyP establishes crosstalk between mTOR and Wnt/β-catenin signaling in endothelial cells. Background Inorganic polyphosphate (polyP) elicits intracellular signaling responses in endothelial cells through activation of mTOR complexes 1 and 2. Glycogen synthase kinase 3 (GSK-3) is known to be a negative regulator of mTOR and Wnt/β-catenin signaling pathways. Objective The objective of this study was to investigate the effect of polyP on the expression, degradation and subcellular localization of the Wnt/β-catenin target gene, cyclin D1, in endothelial cells. Methods Regulation of cyclin D1 expression, phosphorylation and subcellular localization by polyP or platelet releasates was monitored in the absence and presence of pharmacological inhibitors and/or siRNA for specific molecules of the upstream mTOR/Wnt/β-catenin signaling network by established methods. Results Both synthetic polyP and boiled-platelet releasates induced the phosphorylation-dependent inactivation of GSK-3, thereby increasing the expression and nuclear localization, but inhibiting the degradation of cyclin D1. Inhibitors of mTORC1 (PI3K, AKT, PLC, PKC), rapamycin and siRNA for raptor (mTORC1-specific component) and β-catenin, all inhibited polyP-mediated regulation of cyclin D1 expression, phosphorylation and subcellular localization in endothelial cells. The signaling effect of polyP was effectively inhibited by the recombinant extracellular domain of the receptor for advanced glycation end products (RAGE) and/or by the RAGE siRNA. Specific pharmacological inhibitors and siRNA knockdown of ERK1/2 and NF-κB pathways indicated that polyP-mediated cyclin D1 expression and nuclear localization are IKK

  3. Loss of claudin-3 expression induces IL6/gp130/Stat3 signaling to promote colon cancer malignancy by hyperactivating Wnt/β-catenin signaling.

    Science.gov (United States)

    Ahmad, R; Kumar, B; Chen, Z; Chen, X; Müller, D; Lele, S M; Washington, M K; Batra, S K; Dhawan, P; Singh, A B

    2017-11-23

    The hyperactivated Wnt/β-catenin signaling acts as a switch to induce epithelial to mesenchymal transition and promote colorectal cancer. However, due to its essential role in gut homeostasis, therapeutic targeting of this pathway has proven challenging. Additionally, IL-6/Stat-3 signaling, activated by microbial translocation through the dysregulated mucosal barrier in colon adenomas, facilitates the adenoma to adenocarcinomas transition. However, inter-dependence between these signaling pathways and key mucosal barrier components in regulating colon tumorigenesis and cancer progression remains unclear. In current study, we have discovered, using a comprehensive investigative regimen, a novel and tissue-specific role of claudin-3, a tight junction integral protein, in inhibiting colon cancer progression by serving as the common rheostat of Stat-3 and Wnt-signaling activation. Loss of claudin-3 also predicted poor patient survival. These findings however contrasted an upregulated claudin-3 expression in other cancer types and implicated role of the epigenetic regulation. Claudin-3-/- mice revealed dedifferentiated and leaky colonic epithelium, and developed invasive adenocarcinoma when subjected to colon cancer. Wnt-signaling hyperactivation, albeit in GSK-3β independent manner, differentiated colon cancer in claudin-3-/- mice versus WT-mice. Claudin-3 loss also upregulated the gp130/IL6/Stat3 signaling in colonic epithelium potentially assisted by infiltrating immune components. Genetic and pharmacological studies confirmed that claudin-3 loss induces Wnt/β-catenin activation, which is further exacerbated by Stat-3-activation and help promote colon cancer. Overall, these novel findings identify claudin-3 as a therapeutic target for inhibiting overactivation of Wnt-signaling to prevent CRC malignancy.

  4. Location-specific effect of microbiota and MyD88-dependent signaling on Wnt/β-catenin pathway and intestinal stem cells.

    Science.gov (United States)

    Moossavi, Shirin

    2014-01-01

    Intestinal homeostasis depends on the proper activity of the intestinal stem cells (ISCs) and an appropriate host response to the normal resident microbiota. The question on the effect of microbiota on ISCs behavior has not been addressed yet. Canonical Wnt pathway and ISC gene expression signature was compared in germfree vs. conventional and MyD88(-/-) vs. Myd88(+/+) mice based on publicly available gene expression data sets. Microbiota and MyD88-dependent signaling have distinct effects on the Wnt pathway and ISC at gene expression level. In addition, the effect of microbiota and MyD88-dependent signaling on Wnt pathway and ISCs show regional variation. The net effect of microbiota on Wnt pathway and ISCs cannot be inferred from the available data. Nonetheless, the data are suggestive of a potential regulatory mechanism of the Wnt pathway by the microbiota and plausibly by any alteration in the microbiota composition.

  5. Focal Adhesion Kinase Is Required for Intestinal Regeneration and Tumorigenesis Downstream of Wnt/c-Myc Signaling

    Science.gov (United States)

    Ashton, Gabrielle H.; Morton, Jennifer P.; Myant, Kevin; Phesse, Toby J.; Ridgway, Rachel A.; Marsh, Victoria; Wilkins, Julie A.; Athineos, Dimitris; Muncan, Vanesa; Kemp, Richard; Neufeld, Kristi; Clevers, Hans; Brunton, Valerie; Winton, Douglas J.; Wang, Xiaoyan; Sears, Rosalie C.; Clarke, Alan R.; Frame, Margaret C.; Sansom, Owen J.

    2012-01-01

    SUMMARY The intestinal epithelium has a remarkable capacity to regenerate after injury and DNA damage. Here, we show that the integrin effector protein Focal Adhesion Kinase (FAK) is dispensable for normal intestinal homeostasis and DNA damage signaling, but is essential for intestinal regeneration following DNA damage. Given Wnt/c-Myc signaling is activated following intestinal regeneration, we investigated the functional importance of FAK following deletion of the Apc tumor suppressor protein within the intestinal epithelium. Following Apc loss, FAK expression increased in a c-Myc-dependent manner. Codeletion of Apc and Fak strongly reduced proliferation normally induced following Apc loss, and this was associated with reduced levels of phospho-Akt and suppression of intestinal tumorigenesis in Apc heterozygous mice. Thus, FAK is required downstream of Wnt Signaling, for Akt/mTOR activation, intestinal regeneration, and tumorigenesis. Importantly, this work suggests that FAK inhibitors may suppress tumorigenesis in patients at high risk of developing colorectal cancer. PMID:20708588

  6. Device for data-acquisition from transient signals: kinetic considerations

    OpenAIRE

    Sampedro, A. Sanchez; Vives, S. Sagrado; Calatayud, J. Martinez

    1990-01-01

    This paper reports on the evaluation and testing of a home-made device. Data-acquisition, treatment of transient signals and the hardware and software involved are discussed. Some practical aspects are developed in order to power the autonomy of procedures using the device. Kinetic and multi-signal calculations are considered in order to cover the actual tendencies in continuous-flow analysis. Somepractical advantages versus the use of classical chart recorders or commercial computerized-inst...

  7. Contrasting expression of canonical Wnt signaling reporters TOPGAL, BATGAL and Axin2(LacZ during murine lung development and repair.

    Directory of Open Access Journals (Sweden)

    Denise Al Alam

    Full Text Available Canonical WNT signaling plays multiple roles in lung organogenesis and repair by regulating early progenitor cell fates: investigation has been enhanced by canonical Wnt reporter mice, TOPGAL, BATGAL and Axin2(LacZ. Although widely used, it remains unclear whether these reporters convey the same information about canonical Wnt signaling. We therefore compared beta-galactosidase expression patterns in canonical Wnt signaling of these reporter mice in whole embryo versus isolated prenatal lungs. To determine if expression varied further during repair, we analyzed comparative pulmonary expression of beta-galactosidase after naphthalene injury. Our data show important differences between reporter mice. While TOPGAL and BATGAL lines demonstrate Wnt signaling well in early lung epithelium, BATGAL expression is markedly reduced in late embryonic and adult lungs. By contrast, Axin2(LacZ expression is sustained in embryonic lung mesenchyme as well as epithelium. Three days into repair after naphthalene, BATGAL expression is induced in bronchial epithelium as well as TOPGAL expression (already strongly expressed without injury. Axin2(LacZ expression is increased in bronchial epithelium of injured lungs. Interestingly, both TOPGAL and Axin2(LacZ are up regulated in parabronchial smooth muscle cells during repair. Therefore the optimal choice of Wnt reporter line depends on whether up- or down-regulation of canonical Wnt signal reporting in either lung epithelium or mesenchyme is being compared.

  8. A targeted glycan-related gene screen reveals heparan sulfate proteoglycan sulfation regulates WNT and BMP trans-synaptic signaling.

    Directory of Open Access Journals (Sweden)

    Neil Dani

    Full Text Available A Drosophila transgenic RNAi screen targeting the glycan genome, including all N/O/GAG-glycan biosynthesis/modification enzymes and glycan-binding lectins, was conducted to discover novel glycan functions in synaptogenesis. As proof-of-product, we characterized functionally paired heparan sulfate (HS 6-O-sulfotransferase (hs6st and sulfatase (sulf1, which bidirectionally control HS proteoglycan (HSPG sulfation. RNAi knockdown of hs6st and sulf1 causes opposite effects on functional synapse development, with decreased (hs6st and increased (sulf1 neurotransmission strength confirmed in null mutants. HSPG co-receptors for WNT and BMP intercellular signaling, Dally-like Protein and Syndecan, are differentially misregulated in the synaptomatrix of these mutants. Consistently, hs6st and sulf1 nulls differentially elevate both WNT (Wingless; Wg and BMP (Glass Bottom Boat; Gbb ligand abundance in the synaptomatrix. Anterograde Wg signaling via Wg receptor dFrizzled2 C-terminus nuclear import and retrograde Gbb signaling via synaptic MAD phosphorylation and nuclear import are differentially activated in hs6st and sulf1 mutants. Consequently, transcriptional control of presynaptic glutamate release machinery and postsynaptic glutamate receptors is bidirectionally altered in hs6st and sulf1 mutants, explaining the bidirectional change in synaptic functional strength. Genetic correction of the altered WNT/BMP signaling restores normal synaptic development in both mutant conditions, proving that altered trans-synaptic signaling causes functional differentiation defects.

  9. The STAT3-miRNA-92-Wnt Signaling Pathway Regulates Spheroid Formation and Malignant Progression in Ovarian Cancer.

    Science.gov (United States)

    Chen, Min-Wei; Yang, Shu-Ting; Chien, Ming-Hsien; Hua, Kuo-Tai; Wu, Chin-Jui; Hsiao, S M; Lin, Hao; Hsiao, Michael; Su, Jen-Liang; Wei, Lin-Hung

    2017-04-15

    Ovarian cancer spheroids constitute a metastatic niche for transcoelomic spread that also engenders drug resistance. Spheroid-forming cells express active STAT3 signaling and display stem cell-like properties that may contribute to ovarian tumor progression. In this study, we show that STAT3 is hyperactivated in ovarian cancer spheroids and that STAT3 disruption in this setting is sufficient to relieve chemoresistance. In an NSG murine model of human ovarian cancer, STAT3 signaling regulated spheroid formation and self-renewal properties, whereas STAT3 attenuation reduced tumorigenicity. Mechanistic investigations revealed that Wnt signaling was required for STAT3-mediated spheroid formation. Notably, the Wnt antagonist DKK1 was the most strikingly upregulated gene in response to STAT3 attenuation in ovarian cancer cells. STAT3 signaling maintained stemness and interconnected Wnt/β-catenin signaling via the miR-92a/DKK1-regulatory pathways. Targeting STAT3 in combination with paclitaxel synergistically reduced peritoneal seeding and prolonged survival in a murine model of intraperitoneal ovarian cancer. Overall, our findings define a STAT3-miR-92a-DKK1 pathway in the generation of cancer stem-like cells in ovarian tumors, with potential therapeutic applications in blocking their progression. Cancer Res; 77(8); 1955-67. ©2017 AACR. ©2017 American Association for Cancer Research.

  10. Retinoic acid is required and Fgf, Wnt, and Bmp signaling inhibit posterior lateral line placode induction in zebrafish.

    Science.gov (United States)

    Nikaido, Masataka; Navajas Acedo, Joaquin; Hatta, Kohei; Piotrowski, Tatjana

    2017-11-15

    The lateral line system is a mechanosensory systems present in aquatic animals. The anterior and posterior lateral lines develop from anterior and posterior lateral line placodes (aLLp and pLLp), respectively. Although signaling molecules required for the induction of other cranial placodes have been well studied, the molecular mechanisms underlying formation of the lateral line placodes are unknown. In this study we tested the requirement of multiple signaling pathways, such as Wnt, Bmp Fgf, and Retinoic Acid for aLLp and pLLp induction. We determined that aLLp specification requires Fgf signaling, whilst pLLp specification requires retinoic acid which inhibits Fgf signaling. pLLp induction is also independent of Wnt and Bmp activities, even though these pathways limit the boundaries of the pLLp. This is the first report that the aLLp and pLLp depend on different inductive mechanisms and that pLLp induction requires the inhibition of Fgf, Wnt and Bmp signaling. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Integration of BMP/Wnt signaling to control clonal growth of limbal epithelial progenitor cells by niche cells

    Directory of Open Access Journals (Sweden)

    Bo Han

    2014-03-01

    Full Text Available Both BMP and Wnt signaling control stem cells in bulge/dermal papilla, intestinal crypt, and bone marrow. To explore their roles in the limbal niche, which govern corneal epithelial homeostasis, we established an in vitro model of sphere growth by reunion between single limbal epithelial progenitor cells (LEPCs and aggregates of limbal niche cells (LNCs in 3D Matrigel. Compared to LEPCs alone, spheres formed by LEPC+LNC exhibited higher clonal growth and less corneal epithelial differentiation. Furthermore, pSmad1/5/8 was in the nucleus of LEPCs, but not LNCs, and correlated with upregulation of BMP1, BMP3, BMP4, all three BMP receptors, and BMP target genes. Inactivation of BMP signaling in LNCs was correlated with upregulation of noggin preferentially expressed by LNCs. Additionally, β-catenin was stabilized in the perinuclear cytoplasm in LEPCs and correlated with upregulation of Wnt7A and FZD5 preferentially expressed by LEPCs. Inactivation of Wnt signaling in LNCs was correlated with upregulation of DKK1/2 by LNCs. Addition of XAV939 that expectedly downregulated perinuclear β-catenin in LEPCs led to significant reduction of epithelial clonal growth, but upregulated all three BMP receptors and downregulated LNC-derived noggin, resulting in activation of BMP signaling in LNCs. Addition of noggin that expectedly downregulated nuclear localization of pSmad1/5/8 in LEPCs led to nuclear localization of β-catenin in larger LEPCs but membrane relocation of β-catenin in smaller LEPCs and significant upregulation of DKK1/2. Hence, balancing acts between Wnt signaling and BMP signaling exist not only within LEPCs but also between LEPCs and LNCs to regulate clonal growth of LEPCs.

  12. Wnt-reporter expression pattern in the mouse intestine during homeostasis

    Directory of Open Access Journals (Sweden)

    Carroll Kevin H

    2008-12-01

    Full Text Available Abstract Background The canonical Wnt signaling pathway is a known regulator of cell proliferation during development and maintenance of the intestinal epithelium. Perturbations in this pathway lead to aberrant epithelial proliferation and intestinal cancer. In the mature intestine, proliferation is confined to the relatively quiescent stem cells and the rapidly cycling transient-amplifying cells in the intestinal crypts. Although the Wnt signal is believed to regulate all proliferating intestinal cells, surprisingly, this has not been thoroughly demonstrated. This important determination has implications on intestinal function, especially during epithelial expansion and regeneration, and warrants an extensive characterization of Wnt-activated cells. Methods To identify intestinal epithelial cells that actively receive a Wnt signal, we analyzed intestinal Wnt-reporter expression patterns in two different mouse lines using immunohistochemistry, enzymatic activity, in situ hybridization and qRT-PCR, then corroborated results with reporter-independent analyses. Wnt-receiving cells were further characterized for co-expression of proliferation markers, putative stem cell markers and cellular differentiation markers using an immunohistochemical approach. Finally, to demonstrate that Wnt-reporter mice have utility in detecting perturbations in intestinal Wnt signaling, the reporter response to gamma-irradiation was examined. Results Wnt-activated cells were primarily restricted to the base of the small intestinal and colonic crypts, and were highest in numbers in the proximal small intestine, decreasing in frequency in a gradient toward the large intestine. Interestingly, the majority of the Wnt-reporter-expressing cells did not overlap with the transient-amplifying cell population. Further, while Wnt-activated cells expressed the putative stem cell marker Musashi-1, they did not co-express DCAMKL-1 or cell differentiation markers. Finally, gamma

  13. Noncanonical WNT-5B signaling induces inflammatory responses in human lung fibroblasts

    NARCIS (Netherlands)

    van Dijk, Eline M.; Menzen, Mark H.; Spanjer, Anita I. R.; Middag, Laurens D. C.; Brandsma, Corry-Anke A.; Gosens, Reinoud

    2016-01-01

    COPD is a progressive chronic lung disease characterized by pulmonary inflammation. Several recent studies indicate aberrant expression of WNT ligands and Frizzled receptors in the disease. For example, WNT-5A/B ligand expression was recently found to be increased in lung fibroblasts of COPD

  14. Wnt5a controls Notch1 signaling through CaMKII-mediated degradation of the SMRT corepressor protein.

    Science.gov (United States)

    Ann, Eun-Jung; Kim, Hwa-Young; Seo, Mi-Sun; Mo, Jung-Soon; Kim, Mi-Yeon; Yoon, Ji-Hye; Ahn, Ji-Seon; Park, Hee-Sae

    2012-10-26

    Serine-threonine Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor. The kinase activity of CaMKII was essential for the activation of Notch signaling. We also determined that CaMKII could enhance the association between Notch1-IC and RBP-Jk. Furthermore, the physical association between RBP-Jk and SMRT was substantially suppressed by CaMKII. We demonstrated that CaMKII directly bound and phosphorylated SMRT at Ser-1407, thereby facilitating SMRT translocation from the nucleus to the cytoplasm and proteasome-dependent degradation. These results suggest that CaMKII down-regulated the protein stability of SMRT through proteasomal degradation.

  15. Wnt5a Controls Notch1 Signaling through CaMKII-mediated Degradation of the SMRT Corepressor Protein*

    Science.gov (United States)

    Ann, Eun-Jung; Kim, Hwa-Young; Seo, Mi-Sun; Mo, Jung-Soon; Kim, Mi-Yeon; Yoon, Ji-Hye; Ahn, Ji-Seon; Park, Hee-Sae

    2012-01-01

    Serine-threonine Ca2+/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor. The kinase activity of CaMKII was essential for the activation of Notch signaling. We also determined that CaMKII could enhance the association between Notch1-IC and RBP-Jk. Furthermore, the physical association between RBP-Jk and SMRT was substantially suppressed by CaMKII. We demonstrated that CaMKII directly bound and phosphorylated SMRT at Ser-1407, thereby facilitating SMRT translocation from the nucleus to the cytoplasm and proteasome-dependent degradation. These results suggest that CaMKII down-regulated the protein stability of SMRT through proteasomal degradation. PMID:22888005

  16. Wnt/β‐catenin‐signaling and the formation of Müller glia‐derived progenitors in the chick retina

    National Research Council Canada - National Science Library

    Gallina, Donika; Palazzo, Isabella; Steffenson, Lillia; Todd, Levi; Fischer, Andy J

    2016-01-01

    ...‐signaling influences the formation of MGPCs in the chick retina in vivo . In NMDA‐damaged retinas where MGPCs are known to form, we find dynamic changes in retinal levels of potential readouts of Wnt...

  17. Detection of transient disturbing signals on PC boards

    Directory of Open Access Journals (Sweden)

    S. Korte

    2008-05-01

    Full Text Available This paper shows a possibility to visualize signal propagation in electronic circuits. Instead of using various galvanic measurement points all over the circuit, a test method is shown which measures the radiated field of the printed circuit board. By use of a 2-dimensional positionable field probe it is possible to get an overview over the signals running on the different parts of the PCB. In order to measure transient disturbing signals and distinguish them from normal device operation, problems of probe design and triggering need to be discussed.

  18. The role of protein phosphatase 2A in regulating Wnt signaling and apoptosis

    Science.gov (United States)

    Li, Xinghai

    Protein phosphatase 2A (PP2A) is a major serine/threonine-specific phosphatase and regulates a significant array of cellular events. This dissertation primarily describes the novel role of PP2A in Wnt signaling and apoptosis. First, PP2A and its B56 regulatory subunit inhibit Wnt signaling in Xenopus. PP2A is required for β- catenin degradation in vitro. A PP2A heterotrimer containing A, C, and B56 subunits was co- immunoprecipitated with axin. A, C, and B56 subunits each have ventralizing ability in Xenopus embryos. B56 was epistatically positioned downstream of GSK3β and axin but upstream of β-catenin. Second, B56-targeted PP2A is required for survival and protects from apoptosis in Drosophila. Loss of A, C, or B56 subunits by RNA interference (RNAi) induced apoptosis in S2 cells, which requires the presence of specific caspases. Epistasis analysis placed B56-targeted PP2A functionally upstream of Apaf-1, Reaper and Hid, and p53. Loss of B56-targeted PP2A in Drosophila embryos by RNAi resulted in abortion of embryo development and this phenotype was rescued by co-RNAi of Drice. Third, two conserved domains in B subunits mediate binding to the A subunit of PP2A. B subunits have no detectable sequence homology among different families. In vitro expression of a series of B56α fragments identified two distinct domains that independently bound to the A subunit. Sequence alignment of these A subunit-binding domains recognized conserved residues in B/PR55 and B'/PR72 family members that serve a similar function. Fourth, to examine whether the B56β gene within 11q12 is a tumor suppressor mutated in neuroblastoma, the DNA and RNA samples from neuroblastoma patients and cell lines were analyzed and no mutations were identified in the coding regions of the B56β gene. Finally, to identify novel regulatory subunits of PP2A in S. cerevisiae , biochemical approaches for purifying PP2A-associated novel regulators were undertaken. Although the A and C subunit complex in the

  19. Wnt/β-catenin signaling is required for development of the exocrine pancreas

    Directory of Open Access Journals (Sweden)

    Sklenka Angela

    2007-01-01

    Full Text Available Abstract Background β-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of β-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that β-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of β-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of β-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of β-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed β-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis. Results Pdx1-cre floxed β-catenin animals were viable but demonstrated small body size and shortened median survival. The pancreata from knockout mice were hypoplastic and histologically demonstrated a striking paucity of exocrine pancreas, acinar to duct metaplasia, but generally intact pancreatic islets containing all lineages of endocrine cells. In animals with extensive acinar hypoplasia, putative hepatocyte transdifferention was occasionally observed. Obvious and uniform pancreatic hypoplasia was observed by embryonic day E16.5. Transcriptional profiling of Pdx1-cre floxed β-catenin embryonic pancreata at E14.5, before there was a morphological phenotype, revealed significant decreases in the β-catenin target gene N-myc, and the basic HLH transcription factor PTF1, and an increase of several pancreatic zymogens compared to control animals. By E16.5, there was a dramatic loss of exocrine markers and an increase in Hoxb4, which is normally expressed anterior to the pancreas. Conclusion We

  20. Methylation of DACT2 promotes papillary thyroid cancer metastasis by activating Wnt signaling.

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    Zhiyan Zhao

    Full Text Available Thyroid cancer is the most common endocrine malignant disease and the incidence is increasing. DACT2 was found frequently methylated in human lung cancer and hepatocellular carcinoma. To explore the epigenetic change and the role of DACT2 in thyroid cancer, 7 thyroid cancer cell lines, 10 cases of non-cancerous thyroid tissue samples and 99 cases of primary thyroid cancer samples were involved in this study. DACT2 was expressed and unmethylated in K1, SW579, FTC-133, TT, W3 and 8505C cell lines. Loss of expression and complete methylation was found in TPC-1 cells. Restoration of DACT2 expression was induced by 5-aza-2'deoxycytidine treatment. It demonstrates that the expression of DACT2 was regulated by promoter region methylation. In human primary papillary thyroid cancer, 64.6% (64/99 was methylated and methylation of DACT2 was related to lymph node metastasis (p<0.01. Re-expression of DACT2 suppresses cell proliferation, invasion and migration in TPC-1 cells. The activity of TCF/LEF was inhibited by DACT2 in wild-type or mutant β-catenin cells. The activity of TCF/LEF was increased by co-transfecting DACT2 and Dvl2 in wild-type or mutant β-catenin cells. Overexpression of wild-type β-catenin promotes cell migration and invasion in DACT2 stably expressed cells. The expression of β-catenin, c-myc, cyclinD1 and MMP-9 were decreased and the level of phosphorylated β-catenin (p-β-catenin was increased after restoration of DACT2 expression in TPC-1 cells. The expression of β-catenin, c-myc, cyclinD1 and MMP-9 were increased and the level of p-β-catenin was reduced after knockdown of DACT2 in W3 and SW579 cells. These results suggest that DACT2 suppresses human papillary thyroid cancer growth and metastasis by inhibiting Wnt signaling. In conclusion, DACT2 is frequently methylated in papillary thyroid cancer. DACT2 expression was regulated by promoter region methylation. DACT2 suppresses papillary thyroid cancer proliferation and metastasis

  1. The roles of EGF and Wnt signaling during patterning of the C. elegans Bγ/δ Equivalence Group

    Directory of Open Access Journals (Sweden)

    Sternberg Paul W

    2009-12-01

    Full Text Available Abstract Background During development, different signaling pathways interact to specify cell fate by regulating transcription factors necessary for fate specification and morphogenesis. In Caenorhabditis elegans, the EGF-Ras and Wnt signaling pathways have been shown to interact to specify cell fate in three equivalence groups: the vulval precursor cells (VPCs, the hook competence group (HCG and P11/12. In the VPCs, HCG and P11/12 pair, EGF and Wnt signaling positively regulate different Hox genes, each of which also functions during fate specification. In the male, EGF-Ras signaling is required to specify the Bγ fate within the Bγ/δ equivalence pair, while Notch signaling is required for Bδ fate specification. In addition, TGF-β signaling by dbl-1/dpp controls ceh-13/labial/Hox1 expression in Bγ. Results We show that EGF-Ras signaling is required for Bγ expression of ceh-13/labial/Hox1. The transcription factors lin-1/ETS and lin-31/Forkhead, functioning downstream of the EGF pathway, as well as sur-2/MED23 (a component of the Mediator complex also control ceh-13 expression in Bγ. In addition, our results indicate that lin-44/Wnt, mom-2/Wnt and lin-17/Fz are necessary to maintain the division of Bγ along a longitudinal axis. We also show that dbl-1/dpp acts either in parallel or downstream of EGF pathway to regulate ceh-13/Hox1 expression in Bγ. Lastly, we find that a dbl-1/dpp null mutation did not cause any vulval or P12 defects and did not enhance vulval and P12 defects of reduction-of-function mutations of components of the EGF pathway. Conclusions ceh-13/labial/Hox1 expression in Bγ is regulated by the EGF pathway and downstream factors lin-1/ETS lin-31/Forkhead and sur-2/MED23. Wnt signaling is required for proper Bγ division, perhaps to orient the Bγ mitotic spindle. Our results suggest that dbl-1/dpp is not required for VPC and P12 specification, highlighting another difference among these EGF-dependent equivalence groups.

  2. Wnt/β-Catenin Signaling Activation beyond Robust Nuclear β-Catenin Accumulation in Nondysplastic Barrett’s Esophagus: Regulation via Dickkopf-1

    Directory of Open Access Journals (Sweden)

    Orestis Lyros

    2015-07-01

    Full Text Available INTRODUCTION: Wnt/β-catenin signaling activation has been reported only during the late steps of Barrett’s esophagus (BE neoplastic progression, but not in BE metaplasia, based on the absence of nuclear β-catenin. However, β-catenin transcriptional activity has been recorded in absence of robust nuclear accumulation. Thus, we aimed to investigate the Wnt/β-catenin signaling in nondysplastic BE. METHODS: Esophageal tissues from healthy and BE patients without dysplasia were analyzed for Wnt target gene expression by quantitative reverse transcription polymerase chain reaction (qRT-PCR and immunohistochemistry. Esophageal squamous (EPC1-& EPC2-hTERT, BE metaplastic (CP-A, and adenocarcinoma (OE33 cell lines were characterized for Wnt activation by qRT-PCR, Western blot, and luciferase assay. Wnt activity regulation was examined by using recombinant Wnt3a and Dickkopf-1 (Dkk1 as well as Dkk1 short interfering RNA. RESULTS: Wnt target genes (AXIN2, c-MYC, Cyclin D1, Dkk1 and Wnt3a were significantly upregulated in nondysplastic BE compared with squamous mucosa. Elevated levels of dephosphorylated β-catenin were detected in nondysplastic BE. Nuclear active β-catenin and TOPflash activity were increased in CP-A and OE33 cells compared with squamous cells. Wnt3a-mediated β-catenin signaling activation was abolished by Dkk1 in CP-A cells. TOPFlash activity was elevated following Dkk1 silencing in CP-A but not in OE33 cells. Dysplastic and esophageal adenocarcinoma tissues demonstrated further Dkk1 and AXIN2 overexpression. CONCLUSIONS: Despite the absence of robust nuclear accumulation, β-catenin is transcriptionally active in nondysplastic BE. Dkk1 overexpression regulates β-catenin signaling in BE metaplastic but not in adenocarcinoma cells, suggesting that early perturbation of Dkk1-mediated signaling suppression may contribute to BE malignant transformation.

  3. PAF-Wnt signaling-induced cell plasticity is required for maintenance of breast cancer cell stemness.

    Science.gov (United States)

    Wang, Xin; Jung, Youn-Sang; Jun, Sohee; Lee, Sunhye; Wang, Wenqi; Schneider, Andrea; Sun Oh, Young; Lin, Steven H; Park, Bum-Joon; Chen, Junjie; Keyomarsi, Khandan; Park, Jae-Il

    2016-02-04

    Cancer stem cells (CSCs) contribute to tumour heterogeneity, therapy resistance and metastasis. However, the regulatory mechanisms of cancer cell stemness remain elusive. Here we identify PCNA-associated factor (PAF) as a key molecule that controls cancer cell stemness. PAF is highly expressed in breast cancer cells but not in mammary epithelial cells (MECs). In MECs, ectopic expression of PAF induces anchorage-independent cell growth and breast CSC marker expression. In mouse models, conditional PAF expression induces mammary ductal hyperplasia. Moreover, PAF expression endows MECs with a self-renewing capacity and cell heterogeneity generation via Wnt signalling. Conversely, ablation of endogenous PAF induces the loss of breast cancer cell stemness. Further cancer drug repurposing approaches reveal that NVP-AUY922 downregulates PAF and decreases breast cancer cell stemness. Our results unveil an unsuspected role of the PAF-Wnt signalling axis in modulating cell plasticity, which is required for the maintenance of breast cancer cell stemness.

  4. EET intervention on Wnt1, NOV, and HO-1 signaling prevents obesity-induced cardiomyopathy in obese mice.

    Science.gov (United States)

    Cao, Jian; Singh, Shailendra P; McClung, John A; Joseph, Gregory; Vanella, Luca; Barbagallo, Ignazio; Jiang, Houli; Falck, John R; Arad, Michael; Shapiro, Joseph I; Abraham, Nader G

    2017-08-01

    We have previously reported that epoxyeicosatrienoic acid (EET) has multiple beneficial effects on vascular function; in addition to its antiapoptotic action, it increases insulin sensitivity and inhibits inflammation. To uncover the signaling mechanisms by which EET reduces cardiomyopathy, we hypothesized that EET infusion might ameliorate obesity-induced cardiomyopathy by improving heme oxygenase (HO)-1, Wnt1, thermogenic gene levels, and mitochondrial integrity in cardiac tissues and improved pericardial fat phenotype. EET reduced levels of fasting blood glucose and proinflammatory adipokines, including nephroblastoma overexpressed (NOV) signaling, while increasing echocardiographic fractional shortening and O2 consumption. Of interest, we also noted a marked improvement in mitochondrial integrity, thermogenic genes, and Wnt 1 and HO-1 signaling mechanisms. Knockout of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in EET-treated mice resulted in a reversal of these beneficial effects including a decrease in myocardial Wnt1 and HO-1 expression and an increase in NOV. To further elucidate the effects of EET on pericardial adipose tissues, we observed EET treatment increases in adiponectin, PGC-1α, phospho-AMP-activated protein kinase, insulin receptor phosphorylation, and thermogenic genes, resulting in a "browning" pericardial adipose phenotype under high-fat diets. Collectively, these experiments demonstrate that an EET agonist increased Wnt1 and HO-1 signaling while decreasing NOV pathways and the progression of cardiomyopathy. Furthermore, this report presents a portal into potential therapeutic approaches for the treatment of heart failure and metabolic syndrome.NEW & NOTEWORTHY The mechanism by which EET acts on obesity-induced cardiomyopathy is unknown. Here, we describe a previously unrecognized function of EET infusion that inhibits nephroblastoma overexpressed (NOV) levels and activates Wnt1, hence identifying NOV inhibition

  5. A pedagogical walkthrough of computational modeling and simulation of Wnt signaling pathway using static causal models in MATLAB

    OpenAIRE

    Sinha, Shriprakash

    2016-01-01

    Simulation study in systems biology involving computational experiments dealing with Wnt signaling pathways abound in literature but often lack a pedagogical perspective that might ease the understanding of beginner students and researchers in transition, who intend to work on the modeling of the pathway. This paucity might happen due to restrictive business policies which enforce an unwanted embargo on the sharing of important scientific knowledge. A tutorial introduction to computational mo...

  6. A pedagogical walkthrough of computational modeling and simulation of Wnt signaling pathway using static causal models in MATLAB.

    Science.gov (United States)

    Sinha, Shriprakash

    2016-12-01

    Simulation study in systems biology involving computational experiments dealing with Wnt signaling pathways abound in literature but often lack a pedagogical perspective that might ease the understanding of beginner students and researchers in transition, who intend to work on the modeling of the pathway. This paucity might happen due to restrictive business policies which enforce an unwanted embargo on the sharing of important scientific knowledge. A tutorial introduction to computational modeling of Wnt signaling pathway in a human colorectal cancer dataset using static Bayesian network models is provided. The walkthrough might aid biologists/informaticians in understanding the design of computational experiments that is interleaved with exposition of the Matlab code and causal models from Bayesian network toolbox. The manuscript elucidates the coding contents of the advance article by Sinha (Integr. Biol. 6:1034-1048, 2014) and takes the reader in a step-by-step process of how (a) the collection and the transformation of the available biological information from literature is done, (b) the integration of the heterogeneous data and prior biological knowledge in the network is achieved, (c) the simulation study is designed, (d) the hypothesis regarding a biological phenomena is transformed into computational framework, and (e) results and inferences drawn using d -connectivity/separability are reported. The manuscript finally ends with a programming assignment to help the readers get hands-on experience of a perturbation project. Description of Matlab files is made available under GNU GPL v3 license at the Google code project on https://code.google.com/p/static-bn-for-wnt-signaling-pathway and https: //sites.google.com/site/shriprakashsinha/shriprakashsinha/projects/static-bn-for-wnt-signaling-pathway. Latest updates can be found in the latter website.

  7. Methylprednisolone promotes recovery of neurological function after spinal cord injury: association with Wnt/β-catenin signaling pathway activation

    Directory of Open Access Journals (Sweden)

    Gong-biao Lu

    2016-01-01

    Full Text Available Some studies have indicated that the Wnt/β-catenin signaling pathway is activated following spinal cord injury, and expression levels of specific proteins, including low-density lipoprotein receptor related protein-6 phosphorylation, β-catenin, and glycogen synthase kinase-3β, are significantly altered. We hypothesized that methylprednisolone treatment contributes to functional recovery after spinal cord injury by inhibiting apoptosis and activating the Wnt/β-catenin signaling pathway. In the current study, 30 mg/kg methylprednisolone was injected into rats with spinal cord injury immediately post-injury and at 1 and 2 days post-injury. Basso, Beattie, and Bresnahan scores showed that methylprednisolone treatment significantly promoted locomotor functional recovery between 2 and 6 weeks post-injury. The number of surviving motor neurons increased, whereas the lesion size significantly decreased following methylprednisolone treatment at 7 days post-injury. Additionally, caspase-3, caspase-9, and Bax protein expression levels and the number of apoptotic cells were reduced at 3 and 7 days post-injury, while Bcl-2 levels at 7 days post-injury were higher in methylprednisolone-treated rats compared with saline-treated rats. At 3 and 7 days post-injury, methylprednisolone up-regulated expression and activation of the Wnt/β-catenin signaling pathway, including low-density lipoprotein receptor related protein-6 phosphorylation, β-catenin, and glycogen synthase kinase-3β phosphorylation. These results indicate that methylprednisolone-induced neuroprotection may correlate with activation of the Wnt/β-catenin signaling pathway.

  8. Exogenous Activation of Wnt/β-Catenin Signaling Attenuates Binge Alcohol-Induced Deficient Bone Fracture Healing

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    Lauing, Kristen L.; Sundaramurthy, Sumana; Nauer, Rachel K.; Callaci, John J.

    2014-01-01

    Aims: Excessive alcohol consumption is associated with fracture non-union. Canonical Wnt pathway signaling activity regulates normal fracture healing. We previously demonstrated that binge alcohol exposure modulates β-catenin levels in the fracture callus of mice. Here, we sought to determine whether exogenous enhancement β-catenin signaling activity could restore normal fracture healing to binge-exposed mice. Methods: C57BL/6 male mice were exposed to episodic alcohol or saline for 6 total days of alcohol exposure over a 2-week period. Following alcohol exposure, mice were subjected to a stabilized mid-shaft tibia fracture. Beginning 4 days post-injury, mice received daily injections of either lithium chloride or saline subcutaneously. Protein levels of activated, inactivated, and total β-catenin and GSK-3β in fracture calluses were measured at post-injury day 9. Biomechanical strength testing and histology of callus tissue was assessed at post fracture day 14. Results: Binge alcohol was associated with decreased callus biomechanical strength, and reduced cartilaginous callus formation. Alcohol decreased levels of callus-associated activated β-catenin while concomitantly increasing the levels of inactive β-catenin at post-injury day 9. Alcohol also increased callus associated activated GSK-3β at post-injury day 9. Lithium chloride (an inhibitor of GSK-3β) treatment increased activated β-catenin protein levels, significantly decreased activated GSK-3β and restored cartilaginous callus formation and endochondral ossification. Conclusion: These data link alcohol-impaired fracture healing with deregulation of Canonical Wnt signaling activity in the fracture callus. Exogenous activation of the Wnt pathway using LiCl attenuated the damaging effects of binge alcohol exposure on the fracture healing process by modulating canonical Wnt signaling activity. PMID:24627571

  9. Wnt/Ca2+/NFAT Signaling Maintains Survival of Ph+ Leukemia Cells upon Inhibition of Bcr-Abl

    OpenAIRE

    Gregory, Mark A.; Phang, Tzu L.; Neviani, Paolo; Alvarez-Calderon, Francesca; Eide, Christopher A.; O'Hare, Thomas; Zaberezhnyy, Vadym; Williams, Richard T.; Druker, Brian J.; Perrotti, Danilo; DeGregori, James

    2010-01-01

    Although Bcr-Abl kinase inhibitors have proven effective in the treatment of chronic myeloid leukemia (CML), they generally fail to completely eradicate Bcr-Abl+ leukemia cells. To identify genes whose inhibition sensitizes Bcr-Abl+ leukemias to killing by Bcr-Abl inhibitors, we performed an RNAi-based synthetic lethal screen with imatinib in CML cells. This screen identified numerous components of a Wnt/Ca2+/NFAT signaling pathway. Antagonism of this pathway led to impaired NFAT activity, de...

  10. Blockage of Wnt/β-Catenin Signaling by Nanoparticles Reduces Survival and Proliferation of CLL Cells In Vitro-Preliminary Study.

    Science.gov (United States)

    Franiak-Pietryga, Ida; Maciejewski, Henryk; Ziemba, Barbara; Appelhans, Dietmar; Voit, Brigitte; Robak, Tadeusz; Jander, Magdalena; Treliński, Jacek; Bryszewska, Maria; Borowiec, Maciej

    2017-11-01

    The Wnt/β-catenin signaling pathway is shown to play a significant role in the control of the survival, proliferation, and differentiation of hematopoietic cells. Studies have confirmed that aberrant activation of canonical Wnt signaling occurs in various forms of leukemia, and is crucial for chronic lymphocytic leukemia (CLL) pathogenesis. The aim of the study is to evaluate the influence of maltotriose (M3) modified fourth generation poly(propylene imine) dendrimers (PPI-G4) on Wnt/β-catenin pathway gene expression in CLL (MEC-1) cells and to compare these findings with those obtained with fludarabine (FA). Microarray data analysis reveals seven of 19 Wnt/β-catenin pathway genes whose expression changes significantly during dendrimer and FA treatment: WNT10A, WNT6, and CDH1 among others. PPI-G4-M3 is already known to influence MEC-1 cell apoptosis and proliferation. The obtained results suggest that the reduction in cell survival under the influence of glycodendrimers and FA may be due to loss of Wnt signaling. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. VDR Activation Reduces Proteinuria and High-Glucose-Induced Injury of Kidneys and Podocytes by Regulating Wnt Signaling Pathway.

    Science.gov (United States)

    Guo, Jia; Lu, Congqun; Zhang, Fangxing; Yu, Haixia; Zhou, Mengwen; He, Meixia; Wang, Chunyan; Zhao, Zhanzheng; Liu, Zhangsuo

    2017-01-01

    Diabetic nephropathy (DN) is a major cause of end-stage renal disease and proteinuria is one of the most prominent clinical manifestations. The expression of Vitamin D receptor (VDR) in patients with chronic kidney diseases was decreased, while VDR agonists could partially alleviate the proteinuria of DN in animal models. The present study was designed to determine the expression of VDR in renal tissues and its relationship with proteinuria the diabetic model db/db mice. The regulation effects of VDR on the Wnt signaling pathway were analyzed using RNA interference and VDR agonist paricalcitol. With the increase in age of the db/db mice, the VDR protein and mRNA levels in renal tissues were decreased, proteinuria increased, and the protein and mRNA levels of GSK-3β of and β-catenin increased. Paricalcitol treatment resulted in the up-regulation of VDR and down-regulation of GSK-3β and β-catenin, indicating that VDR had a regulatory effect on the Wnt signaling pathway. VDR activation could reduce proteinuria of DN mice and alleviate high-glucose-induced injury of kidneys and podocytes by regulating the key molecules of Wnt signaling pathway. © 2017 The Author(s). Published by S. Karger AG, Basel.

  12. Chromomycins A2 and A3 from marine actinomycetes with TRAIL resistance-overcoming and Wnt signal inhibitory activities.

    Science.gov (United States)

    Toume, Kazufumi; Tsukahara, Kentaro; Ito, Hanako; Arai, Midori A; Ishibashi, Masami

    2014-06-05

    A biological screening study of an actinomycetes strain assembly was conducted using a cell-based cytotoxicity assay. The CKK1019 strain was isolated from a sea sand sample. Cytotoxicity-guided fractionation of the CKK1019 strain culture broth, which exhibited cytotoxicity, led to the isolation of chromomycins A2 (1) and A3 (2). 1 and 2 showed potent cytotoxicity against the human gastric adenocarcinoma (AGS) cell line (IC50 1; 1.7 and 2; 22.1 nM), as well as strong inhibitory effects against TCF/β-catenin transcription (IC50 1; 1.8 and 2; 15.9 nM). 2 showed the ability to overcome tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) resistance. To the best of our knowledge, the effects of chromomycins A2 (1) and A3 (2) on TRAIL resistance-overcoming activity, and on the Wnt signaling pathway, have not been reported previously. Thus, 1 and 2 warrant potential drug lead studies in relation to TRAIL-resistant and Wnt signal-related diseases and offer potentially useful chemical probes for investigating TRAIL resistance and the Wnt signaling pathway.

  13. Chromomycins A2 and A3 from Marine Actinomycetes with TRAIL Resistance-Overcoming and Wnt Signal Inhibitory Activities

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    Kazufumi Toume

    2014-06-01

    Full Text Available A biological screening study of an actinomycetes strain assembly was conducted using a cell-based cytotoxicity assay. The CKK1019 strain was isolated from a sea sand sample. Cytotoxicity-guided fractionation of the CKK1019 strain culture broth, which exhibited cytotoxicity, led to the isolation of chromomycins A2 (1 and A3 (2. 1 and 2 showed potent cytotoxicity against the human gastric adenocarcinoma (AGS cell line (IC50 1; 1.7 and 2; 22.1 nM, as well as strong inhibitory effects against TCF/β-catenin transcription (IC50 1; 1.8 and 2; 15.9 nM. 2 showed the ability to overcome tumor necrosis factor (TNF-related apoptosis-inducing ligand (TRAIL resistance. To the best of our knowledge, the effects of chromomycins A2 (1 and A3 (2 on TRAIL resistance-overcoming activity, and on the Wnt signaling pathway, have not been reported previously. Thus, 1 and 2 warrant potential drug lead studies in relation to TRAIL-resistant and Wnt signal-related diseases and offer potentially useful chemical probes for investigating TRAIL resistance and the Wnt signaling pathway.

  14. Daucosterol Inhibits the Proliferation, Migration, and Invasion of Hepatocellular Carcinoma Cells via Wnt/β-Catenin Signaling

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    Junquan Zeng

    2017-06-01

    Full Text Available Hepatocellular carcinoma (HCC is one of the leading causes of cancer-related death worldwide. The purpose of this study was to determine the effects of daucosterol on HCC by investigating Wnt/β-catenin signaling. In this study, HepG2 and SMMC-7721 cells were treated with varying concentrations of daucosterol, and the corresponding inhibitory effects on HCC cells were examined via CCK-8 assays. Cell migration and invasion abilities were detected via transwell assays. β-Catenin and phospho (p-β-catenin levels were analyzed via western blotting. Our results showed that daucosterol reduced the proliferation, migration, and invasion capacities of HCC cells in a concentration-dependent manner. In addition, daucosterol reduced the levels of β-catenin and p-β-catenin in HepG2 and SMMC-7721 cells. Furthermore, the Wnt signaling pathway inhibitor SB-216763 was used to treat HepG2 and SMMC-7721 cells with daucosterol. Our results showed that co-treatment with daucosterol and SB-216763 abolished the effects of daucosterol on cell inhibition ratios, cell migration, and cell invasion. These findings indicated that daucosterol inhibited cell migration and invasion in HCC cells via the Wnt/β-catenin signaling pathway. Therefore, our study highlights the use of daucosterol as a promising therapeutic strategy for HCC treatment.

  15. VDR Activation Reduces Proteinuria and High-Glucose-Induced Injury of Kidneys and Podocytes by Regulating Wnt Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Jia Guo

    2017-08-01

    Full Text Available Background: Diabetic nephropathy (DN is a major cause of end-stage renal disease and proteinuria is one of the most prominent clinical manifestations. The expression of Vitamin D receptor (VDR in patients with chronic kidney diseases was decreased, while VDR agonists could partially alleviate the proteinuria of DN in animal models. The present study was designed to determine the expression of VDR in renal tissues and its relationship with proteinuria the diabetic model db/db mice. Methods: The regulation effects of VDR on the Wnt signaling pathway were analyzed using RNA interference and VDR agonist paricalcitol. Results: With the increase in age of the db/db mice, the VDR protein and mRNA levels in renal tissues were decreased, proteinuria increased, and the protein and mRNA levels of GSK-3β of and β-catenin increased. Paricalcitol treatment resulted in the up-regulation of VDR and down-regulation of GSK-3β and β-catenin, indicating that VDR had a regulatory effect on the Wnt signaling pathway. Conclusion: VDR activation could reduce proteinuria of DN mice and alleviate high-glucose-induced injury of kidneys and podocytes by regulating the key molecules of Wnt signaling pathway.

  16. Effect of Wnt Signaling on the Differentiation of Islet β-Cells from Adipose-Derived Stem Cells

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    Hefei Wang

    2017-01-01

    Full Text Available The Wnt signaling is critical for pancreatic development and islet function; however, its precise effects on the development and function of the β-cells remain controversial. Here we examined mRNA and protein expression of components of the Wnt signaling throughout the differentiation of islet β-cells from adipose-derived stem cells (ADSCs. After induction, ADSCs expressed markers of β-cells, including the insulin, PDX1, and glucagon genes, and the PDX1, CK19, nestin, insulin, and C-peptide proteins, indicating their successful differentiation. Compared with pancreatic adult stem cells (PASCs, the quantities of insulin, GLUT2, and Irs2 mRNA decreased, whereas Gcg, Gck, and Irs1 mRNA increased. Over time, during differentiation, insulin mRNA and protein expression increased, Gcg and Gck mRNA expression increased, Irs1 mRNA expression decreased and then increased, and Irs2 mRNA increased and then decreased (all P0.05. Our results indicate that the Wnt signaling is activated during ADSC differentiation into islet β-cells, but there was no obvious enrichment of nonphosphorylated β-catenin protein.

  17. Regulation of WNT Signaling at the Neuromuscular Junction by the Immunoglobulin Superfamily Protein RIG-3 in Caenorhabditis elegans.

    Science.gov (United States)

    Pandey, Pratima; Bhardwaj, Ashwani; Babu, Kavita

    2017-07-01

    Perturbations in synaptic function could affect the normal behavior of an animal, making it important to understand the regulatory mechanisms of synaptic signaling. Previous work has shown that in Caenorhabditis elegans an immunoglobulin superfamily protein, RIG-3, functions in presynaptic neurons to maintain normal acetylcholine receptor levels at the neuromuscular junction (NMJ). In this study, we elucidate the molecular and functional mechanism of RIG-3. We demonstrate by genetic and BiFC (Bi-molecular Fluorescence Complementation) assays that presynaptic RIG-3 functions by directly interacting with the immunoglobulin domain of the nonconventional Wnt receptor, ROR receptor tyrosine kinase (RTK), CAM-1, which functions in postsynaptic body-wall muscles. This interaction in turn inhibits Wnt/LIN-44 signaling through the ROR/CAM-1 receptor, and allows for maintenance of normal acetylcholine receptor, AChR/ACR-16, levels at the neuromuscular synapse. Further, this work reveals that RIG-3 and ROR/CAM-1 function through the β-catenin/HMP-2 at the NMJ. Taken together, our results demonstrate that RIG-3 functions as an inhibitory molecule of the Wnt/LIN-44 signaling pathway through the RTK, CAM-1. Copyright © 2017 by the Genetics Society of America.

  18. Senescent Atrophic Epidermis Retains Lrig1+ Stem Cells and Loses Wnt Signaling, a Phenotype Shared with CD44KO Mice.

    Science.gov (United States)

    Barnes, Laurent; Saurat, Jean-Hilaire; Kaya, Gürkan

    2017-01-01

    Lrig1 is known to repress the epidermal growth through its inhibitory activity on EGFR, while CD44 promotes it. We analyzed the expression of these molecules in senescent atrophic human epidermis and in the epidermis of CD44KO mice. In normal human epidermis, Lrig1+ cells form clusters located in the basal layer in which CD44 expression is downregulated and Lef1 expression reflects an active Wnt signaling. In senescent atrophic human epidermis, we found retention of Lrig1high+ cells all along the basal layer, forming no clusters, with decrease of CD44 and lef1 expression. In vitro silencing of CD44 indicated that CD44 may be required for Wnt signaling. However, if looking at the ear epidermis of CD44KO mice, we only found a limited interfollicular epidermal atrophy and unchanged Lrig1high+ cells in the hair follicle. Cell lineage tracing further revealed that interfollicular epidermis did lost its self-renewing capacity but that its homeostasis relied on Lrig1-derived keratinocytes migrating from the hair follicle. Therefore, we conclude that CD44 downregulation is part of the phenotype of senescent atrophic human epidermis, and contributes to reduce Wnt signaling and to alter Lrig1high+ stem cell distribution.

  19. Genetic Variants in the Wnt Signaling Pathway Are Not Associated with Survival Outcome of Non-Small Cell Lung Cancer in a Korean Population.

    Science.gov (United States)

    Yoo, Seung Soo; Hong, Mi Jeong; Choi, Jin Eun; Lee, Jang Hyuck; Baek, Sun Ah; Lee, Won Kee; Lee, So Yeon; Lee, Shin Yup; Lee, Jaehee; Cha, Seung Ick; Kim, Chang Ho; Cho, Sukki; Park, Jae Yong

    2016-03-01

    Recently, genetic variants in the WNT signaling pathway have been reported to affect the survival outcome of Caucasian patients with early stage non-small cell lung cancer (NSCLC). We therefore attempted to determine whether these same WNT signaling pathway gene variants had similar impacts on the survival outcome of NSCLC patients in a Korean population. A total of 761 patients with stages I-IIIA NSCLC were enrolled in this study. Eight variants of WNT pathway genes were genotyped and their association with overall survival and disease-free survival were analyzed. None of the eight variants were significantly associated with overall survival or disease-free survival. There were no differences in survival outcome after stratifying the subjects according to age, gender, smoking status, and histological type. These results suggest that genetic variants in the WNT signaling pathway may not affect the survival outcome of NSCLC in a Korean population.

  20. A clinically relevant model of osteoinduction: a process requiring calcium phosphate and BMP/Wnt signalling.

    Science.gov (United States)

    Eyckmans, J; Roberts, S J; Schrooten, J; Luyten, F P

    2010-06-01

    In this study, we investigated a clinically relevant model of in vivo ectopic bone formation utilizing human periosteum derived cells (HPDCs) seeded in a Collagraft carrier and explored the mechanisms by which this process is driven. Bone formation occurred after eight weeks when a minimum of one million HPDCs was loaded on Collagraft carriers and implanted subcutaneously in NMRI nu/nu mice. De novo bone matrix, mainly secreted by the HPDCs, was found juxta-proximal of the calcium phosphate (CaP) granules suggesting that CaP may have triggered the 'osteoinductive program'. Indeed, removal of the CaP granules by ethylenediaminetetraacetic acid decalcification prior to cell seeding and implantation resulted in loss of bone formation. In addition, inhibition of endogenous bone morphogenetic protein and Wnt signalling by overexpression of the secreted antagonists Noggin and Frzb, respectively, also abrogated osteoinduction. Proliferation of the engrafted HPDCs was strongly reduced in the decalcified scaffolds or when seeded with adenovirus-Noggin/Frzb transduced HPDCs indicating that cell division of the engrafted HPDCs is required for the direct bone formation cascade. These data suggest that this model of bone formation is similar to that observed during physiological intramembranous bone development and may be of importance when investigating tissue engineering strategies.

  1. Wnt/β-catenin signaling in osteoblasts regulates global energy metabolism.

    Science.gov (United States)

    Yao, Qianqian; Yu, Caixia; Zhang, Xiuzhen; Zhang, Keqin; Guo, Jun; Song, Lige

    2017-04-01

    Obesity, diabetes and osteoporosis have become a major public heath burden, and understanding the underlying mechanisms of these pathophysiological process will benefit their treatment. Osteoblast lineage cells in charge of the bone formation have been showed to participate in the whole-body energy metabolism. In this study, we identify that wnt/β-catenin signaling in osteoblasts could regulate global energy metabolism, including glucose homeostasis, fat accumulation and energy expenditure. Mice lacking β-catenin specifically in osteoblasts postnatally exhibit decreased bone mass, increased glucose level, decreased insulin production, decreased fat accumulation and increased energy expenditure. Osteocalcin supplement can rescue the impaired glucose balance by improving insulin production but cannot influence the abnormal fat accumulation and energy expenditure. Osteoprotegerin (OPG) overexpression exclusively in osteoblasts in β-catenin deletion mice can normalize not only the decreased bone mass but also the decreased fat accumulation and increased energy expenditure. The effect of β-catenin deletion and OPG overexpression in osteoblasts on global energy metabolism had no relation with inguinal fat browning. These results suggest that the regulation of bone on energy metabolism and fat accumulation is not mediated exclusively by osteocalcin. Our findings may provide a new insight into the regulation of bone on fat accumulation and energy metabolism. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Downregulation of β-catenin blocks fibrosis via Wnt2 signaling in human keloid fibroblasts.

    Science.gov (United States)

    Cai, Yumei; Zhu, Shize; Yang, Weiqun; Pan, Mingmeng; Wang, Chaoyang; Wu, Wenyi

    2017-06-01

    Keloid is a disorder of fibroproliferative diseases that occurs in wounds, characterized by an exaggerated response to injury. The key factor responsible for the disease process has not been identified. This study sought to elucidate the role of β-catenin in the regulation of keloid phenotypes and signaling. Expression of β-catenin in keloid and normal non-keloid samples was measured by real-time polymerase chain reaction. Knockdown of β-catenin was achieved by delivering small interfering RNA to target β-catenin. Cell proliferation, cell cycle progression, and apoptosis of keloid cells were measured by functional assays in vitro. The proteins related to keloid fibrosis were measured by Western blotting. β-catenin expression was significantly upregulated in keloid tissue samples compared with the normal non-keloid age-adjusted skin sample counterparts. Functionally, targeting β-catenin with lipofection-delivered small interfering RNA oligonucleotide inhibited the proliferation and cell cycle arrest in G0/G1 phase and increased apoptosis of fibroblast cells, accompanied by downregulation of Wnt2 and cyclin D1 as well as the phosphorylation level of glycogen synthase kinase 3 beta in the keloid fibrosis. Our study supports a crucial role of β-catenin in the regulation of fibroproliferation and extracellular matrix deposition. Targeting β-catenin using small interfering RNA oligonucleotide may be a promising approach for preventing excessive fibroproliferative development after wound healing and may lead to the development of novel strategies for restoring keloid diseases.

  3. Modulating Wnt signaling to improve cell replacement therapy for Parkinson's disease.

    Science.gov (United States)

    Parish, Clare L; Thompson, Lachlan H

    2014-02-01

    Clinical trials have demonstrated the capacity for dopamine neurons, transplanted ectopically into the striatum, to structurally integrate, restore dopamine transmission, and induce long-term functional benefits for Parkinson's disease (PD) patients. Despite this proof of principle, a number of limitations have hindered the development of cell replacement therapy over the past 20 years, particularly tissue availability, graft survival, and adequate reinnervation of the host brain. With a greater understanding of failure in prior clinical trials, increased knowledge of midbrain dopamine development (now including Wnts), and the development of pluripotent stem cell technologies, we are better equipped than ever to re-address a number of these challenges. This review summarizes the trials, tribulations, and progress in cell replacement therapy for PD. We discuss the prospects of modulating canonical and non-canonical Wnt signaling to improve cell therapy based upon their roles in dopamine neural development and the adult brain. This will include the potential of Wnts to (i) expand fetally derived tissue in vitro and following transplantation, (ii) promote the differentiation of pluripotent stem cells, (iii) increase graft integration and restoration of neural circuitry, and finally (iv) enhance graft survival.

  4. Lawsone derivatives target the Wnt/β-catenin signaling pathway in multidrug-resistant acute lymphoblastic leukemia cells.

    Science.gov (United States)

    Hamdoun, Sami; Fleischer, Edmond; Klinger, Anette; Efferth, Thomas

    2017-12-15

    Multidrug resistance (MDR) represents a serious problem in cancer treatment. One strategy to overcome this obstacle is to identify agents that are selectively lethal to MDR cells. The aim of this study was to discover novel compounds against MDR leukemia and to determine the molecular mechanisms behind collateral sensitivity. A library of 1162 compounds was tested against parental, drug-sensitive CCRF-CEM cells using the resazurin assay. A total of 302 compounds showed reasonable activity (less than 50% cell viability). Eleven out of 30 lawsone derivatives revealed considerable collateral sensitivity in MDR P-glycoprotein (Pgp)-overexpressing CEM/ADR5000 cells. They reduced β-catenin activity in a Wnt/β-catenin reporter cell line. Their activities significantly correlated with apolar desolvation (R = 0.819). Compound (1) (3-hydroxy-1,4-dioxo-N-phenyl-naphthalene-2-carboxamide) was the most active compound and dose-dependently down-regulated protein expression of β-catenin, c-MYC, Pgp and Frizzled 7. By molecular docking, we predicted that compound (1) bound to the palmitoyl-binding groove of the cysteine-rich domain of Frizzled-7 and Frizzled-8. Compound (1) neither stimulated ATPase activity of Pgp nor reactive oxygen species generation, both of which have been previously described as possible mechanisms of collateral sensitivity. Instead, we found that Wnt/β-catenin signaling was selectively inhibited in CEM/ADR5000 cells, but not in CCRF-CEM cells. In conclusion, we found for the first time that the inhibition of Wnt/β-catenin signaling may represent a novel molecular mechanism of collateral sensitivity in MDR cells. Wnt/β-catenin signaling, therefore, represents a potential therapeutic target for the selective killing of Pgp-mediated MDR. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Maternal Wnt/β-catenin signaling coactivates transcription through NF-κB binding sites during Xenopus axis formation.

    Directory of Open Access Journals (Sweden)

    Neil J Armstrong

    Full Text Available Maternal Wnt/β-Catenin signaling establishes a program of dorsal-specific gene expression required for axial patterning in Xenopus. We previously reported that a subset of dorsally expressed genes depends not only on Wnt/β-Catenin stimulation, but also on a MyD88-dependent Toll-like receptor/IL1-receptor (TLR/IL1-R signaling pathway. Here we show that these two signal transduction cascades converge in the nucleus to coactivate gene transcription in blastulae through a direct interaction between β-Catenin and NF-κB proteins. A transdominant inhibitor of NF-κB, ΔNIκBα, phenocopies loss of MyD88 protein function, implicating Rel/NF-κB proteins as selective activators of dorsal-specific gene expression. Sensitive axis formation assays in the embryo demonstrate that dorsalization by Wnt/β-Catenin requires NF-κB protein activity, and vice versa. Xenopus nodal-related 3 (Xnr3 is one of the genes with dual β-Catenin/NF-κB input, and a proximal NF-κB consensus site contributes to the regional activity of its promoter. We demonstrate in vitro binding of Xenopus β-Catenin to several XRel proteins. This interaction is observed in vivo upon Wnt-stimulation. Finally, we show that a synthetic luciferase reporter gene responds to both endogenous and exogenous β-Catenin levels in an NF-κB motif dependent manner. These results suggest that β-Catenin acts as a transcriptional co-activator of NF-κB-dependent transcription in frog primary embryonic cells.

  6. Maternal Wnt/β-Catenin Signaling Coactivates Transcription through NF-κB Binding Sites during Xenopus Axis Formation

    Science.gov (United States)

    Armstrong, Neil J.; Fagotto, François; Prothmann, Christian; Rupp, Ralph A. W.

    2012-01-01

    Maternal Wnt/β-Catenin signaling establishes a program of dorsal-specific gene expression required for axial patterning in Xenopus. We previously reported that a subset of dorsally expressed genes depends not only on Wnt/β-Catenin stimulation, but also on a MyD88-dependent Toll-like receptor/IL1-receptor (TLR/IL1-R) signaling pathway. Here we show that these two signal transduction cascades converge in the nucleus to coactivate gene transcription in blastulae through a direct interaction between β-Catenin and NF-κB proteins. A transdominant inhibitor of NF-κB, ΔNIκBα, phenocopies loss of MyD88 protein function, implicating Rel/NF-κB proteins as selective activators of dorsal-specific gene expression. Sensitive axis formation assays in the embryo demonstrate that dorsalization by Wnt/β-Catenin requires NF-κB protein activity, and vice versa. Xenopus nodal-related 3 (Xnr3) is one of the genes with dual β-Catenin/NF-κB input, and a proximal NF-κB consensus site contributes to the regional activity of its promoter. We demonstrate in vitro binding of Xenopus β-Catenin to several XRel proteins. This interaction is observed in vivo upon Wnt-stimulation. Finally, we show that a synthetic luciferase reporter gene responds to both endogenous and exogenous β-Catenin levels in an NF-κB motif dependent manner. These results suggest that β-Catenin acts as a transcriptional co-activator of NF-κB-dependent transcription in frog primary embryonic cells. PMID:22590521

  7. LATS2 Suppresses Oncogenic Wnt Signaling by Disrupting β-Catenin/BCL9 Interaction

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    Jiong Li

    2013-12-01

    Full Text Available Abnormal activation of Wnt/β-catenin-mediated transcription is associated with a variety of human cancers. Here, we report that LATS2 inhibits oncogenic Wnt/β-catenin-mediated transcription by disrupting the β-catenin/BCL9 interaction. LATS2 directly interacts with β-catenin and is present on Wnt target gene promoters. Mechanistically, LATS2 inhibits the interaction between BCL9 and β-catenin and subsequent recruitment of BCL9, independent of LATS2 kinase activity. LATS2 is downregulated and inversely correlated with the levels of Wnt target genes in human colorectal cancers. Moreover, nocodazole, an antimicrotubule drug, potently induces LATS2 to suppress tumor growth in vivo by targeting β-catenin/BCL9. Our results suggest that LATS2 is not only a key tumor suppressor in human cancer but may also be an important target for anticancer therapy.

  8. Superoxide Dismutase 1 In Vivo Ameliorates Maternal Diabetes Mellitus-Induced Apoptosis and Heart Defects Through Restoration of Impaired Wnt Signaling.

    Science.gov (United States)

    Wang, Fang; Fisher, Steven A; Zhong, Jianxiang; Wu, Yanqing; Yang, Peixin

    2015-10-01

    Oxidative stress is manifested in embryos exposed to maternal diabetes mellitus, yet specific mechanisms for diabetes mellitus-induced heart defects are not defined. Gene deletion of intermediates of Wingless-related integration (Wnt) signaling causes heart defects similar to those observed in embryos from diabetic pregnancies. We tested the hypothesis that diabetes mellitus-induced oxidative stress impairs Wnt signaling, thereby causing heart defects, and that these defects can be rescued by transgenic overexpression of the reactive oxygen species scavenger superoxide dismutase 1 (SOD1). Wild-type (WT) and SOD1-overexpressing embryos from nondiabetic WT control dams and nondiabetic/diabetic WT female mice mated with SOD1 transgenic male mice were analyzed. No heart defects were observed in WT and SOD1 embryos under nondiabetic conditions. WT embryos of diabetic dams had a 26% incidence of cardiac outlet defects that were suppressed by SOD1 overexpression. Insulin treatment reduced blood glucose levels and heart defects. Diabetes mellitus increased superoxide production, canonical Wnt antagonist expression, caspase activation, and apoptosis and suppressed cell proliferation. Diabetes mellitus suppressed Wnt signaling intermediates and Wnt target gene expression in the embryonic heart, each of which were reversed by SOD1 overexpression. Hydrogen peroxide and peroxynitrite mimicked the inhibitory effect of high glucose on Wnt signaling, which was abolished by the SOD1 mimetic, tempol. The oxidative stress of diabetes mellitus impairs Wnt signaling and causes cardiac outlet defects that are rescued by SOD1 overexpression. This suggests that targeting of components of the Wnt5a signaling pathway may be a viable strategy for suppression of congenital heart defects in fetuses of diabetic pregnancies. © 2015 American Heart Association, Inc.

  9. Activation of Vascular Smooth Muscle Parathyroid Hormone Receptor Inhibits Wnt/β-Catenin Signaling and Aortic Fibrosis in Diabetic Arteriosclerosis

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    Cheng, Su-Li; Shao, Jian-Su; Halstead, Linda R.; Distelhorst, Kathryn; Sierra, Oscar; Towler, Dwight A.

    2010-01-01

    Rationale Vascular fibrosis and calcification contribute to diabetic arteriosclerosis, impairing Windkessel physiology necessary for distal tissue perfusion. Wnt family members up-regulated in arteries by the low-grade inflammation of “diabesity” -- stimulate type I collagen expression and osteogenic mineralization of mesenchymal progenitors via β-catenin. Conversely, parathyroid hormone (PTH) inhibits aortic calcification in LDLR (low density lipoprotein receptor)-deficient mice fed high fat diabetogenic diets (HFD). Objective We wished to determine the impact of vascular PTH receptor (PTH1R) activity on arteriosclerotic Wnt/β-catenin signaling in vitro and in vivo. We generated SM-caPTH1R transgenic mice, a model in which the constitutively active PTH1R variant H223R (caPTH1R) is expressed only in the vasculature. Methods and Results The caPTH1R inhibited Wnt/β-catenin signaling, collagen production, and vascular smooth muscle cell (VSMC) proliferation and calcification in vitro. Transgenic SM-caPTH1R;LDLR+/− mice fed HFD develop “diabesity,” with no improvements in fasting serum glucose, cholesterol, weight, body composition, or bone mass vs. LDLR+/− siblings. SM-caPTH1R down-regulated aortic Col1A1, Runx2, and Nox1 expression without altering TNF, Msx2, Wnt7a/b, or Nox4. The SM-caPTH1R transgene decreased aortic β-catenin protein accumulation and signaling in diabetic LDLR+/− mice. Levels of aortic superoxide -- a precursor of peroxide that activates pro-MMP9 and osteogenic signaling in VSMCs -- were suppressed by the SM-caPTH1R transgene. Aortic calcification, collagen accumulation, and wall thickness were concomitantly reduced, enhancing vessel distensibility. Conclusions Cell-autonomous VSMC PTH1R activity inhibits arteriosclerotic Wnt/β-catenin signaling and reduces vascular oxidative stress, thus limiting aortic type I collagen and calcium accrual in diabetic LDLR-deficient mice. PMID:20489161

  10. Wnt16 Signaling Is Required for IL-1β-Induced Matrix Metalloproteinase-13-Regulated Proliferation of Human Stem Cell-Derived Osteoblastic Cells

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    Nobuaki Ozeki

    2016-02-01

    Full Text Available We established a differentiation method for homogeneous α7 integrin-positive human skeletal muscle stem cell (α7+hSMSC-derived osteoblast-like (α7+hSMSC-OB cells, and found that interleukin (IL-1β induces matrix metalloproteinase (MMP-13-regulated proliferation of these cells. These data suggest that MMP-13 plays a potentially unique physiological role in the regeneration of osteoblast-like cells. Here, we examined whether up-regulation of MMP-13 activity by IL-1β was mediated by Wingless/int1 (Wnt signaling and increased the proliferation of osteoblast-like cells. IL-1β increased the mRNA and protein levels of Wnt16 and the Wnt receptor Lrp5/Fzd2. Exogenous Wnt16 was found to increase MMP-13 mRNA, protein and activity, and interestingly, the proliferation rate of these cells. Treatment with small interfering RNAs against Wnt16 and Lrp5 suppressed the IL-1β-induced increase in cell proliferation. We revealed that a unique signaling cascade IL-1β→Wnt16→Lrp5→MMP-13, was intimately involved in the proliferation of osteoblast-like cells, and suggest that IL-1β-induced MMP-13 expression and changes in cell proliferation are regulated by Wnt16.

  11. Fate Specification of Neural Plate Border by Canonical Wnt Signaling and Grhl3 is Crucial for Neural Tube Closure.

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    Kimura-Yoshida, Chiharu; Mochida, Kyoko; Ellwanger, Kristina; Niehrs, Christof; Matsuo, Isao

    2015-06-01

    During primary neurulation, the separation of a single-layered ectodermal sheet into the surface ectoderm (SE) and neural tube specifies SE and neural ectoderm (NE) cell fates. The mechanisms underlying fate specification in conjunction with neural tube closure are poorly understood. Here, by comparing expression profiles between SE and NE lineages, we observed that uncommitted progenitor cells, expressing stem cell markers, are present in the neural plate border/neural fold prior to neural tube closure. Our results also demonstrated that canonical Wnt and its antagonists, DKK1/KREMEN1, progressively specify these progenitors into SE or NE fates in accord with the progress of neural tube closure. Additionally, SE specification of the neural plate border via canonical Wnt signaling is directed by the grainyhead-like 3 (Grhl3) transcription factor. Thus, we propose that the fate specification of uncommitted progenitors in the neural plate border by canonical Wnt signaling and its downstream effector Grhl3 is crucial for neural tube closure. This study implicates that failure in critical genetic factors controlling fate specification of progenitor cells in the neural plate border/neural fold coordinated with neural tube closure may be potential causes of human neural tube defects.

  12. Extracorporeal Shock Wave Rebuilt Subchondral Bone In Vivo and Activated Wnt5a/Ca2+ Signaling In Vitro

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    Lai Yu

    2017-01-01

    Full Text Available Background. This study aimed to identify the optimal extracorporeal shock wave (ESW intensity and to investigate its effect on subchondral bone rebuilt in vivo and Wnt5a/Ca2+ signaling in vitro using an osteoarthritis (OA rat model and bone marrow mesenchymal stem cells (BMMSCs, respectively. Methods. OA rats treated with (OA + ESW group or without (OA group ESW (n=12/group were compared with healthy controls (control group, n=12. Gait patterns and subchondral trabecular bone changes were measured. Western blot and quantitative real-time polymerase chain reaction detected protein expression and gene transcription, respectively. Results. The gait disturbances of OA + ESW group were significantly improved compared with the OA group at 6th and 8th weeks. The micro-CT analysis indicated that the BMD, BSV/BV, BV/TV, Tr.S, and Tr.Th are significantly different between OA group and OA + ESW group. Expression of Wnt5a was increased rapidly after ESW treatment at 0.6 bar and peaked after 30 min. Conclusions. ESW were positive for bone remodeling in joint tibial condyle subchondral bone of OA rat. ESW prevented histological changes in OA and prevented gait disturbance associated with OA progression. Optimal intensity of ESW induced changes in BMMSCs via activation of the Wnt5a/Ca2+ signaling pathway.

  13. Appropriate crypt formation in the uterus for embryo homing and implantation requires Wnt5a-ROR signaling.

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    Cha, Jeeyeon; Bartos, Amanda; Park, Craig; Sun, Xiaofei; Li, Yingju; Cha, Sang-Wook; Ajima, Rieko; Ho, Hsin-Yi Henry; Yamaguchi, Terry P; Dey, Sudhansu K

    2014-07-24

    Embryo homing and implantation occur within a crypt (implantation chamber) at the antimesometrial (AM) pole along the uterus. The mechanism by which this is achieved is not known. Here, we show that villi-like epithelial projections from the main uterine lumen toward the AM pole at regularly spaced intervals that form crypts for embryo implantation were disrupted in mice with uterine loss or gain of function of Wnt5a, or loss of function of both Ror1 and Ror2. This disruption of Wnt5a-ROR signaling resulted in disorderly epithelial projections, crypt formation, embryo spacing, and impaired implantation. These early disturbances under abnormal Wnt5a-ROR signaling were reflected in adverse late pregnancy events, including defective decidualization and placentation, ultimately leading to compromised pregnancy outcomes. This study presents deeper insight regarding the formation of organized epithelial projections for crypt formation and embryo implantation for pregnancy success. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Regulation of the Wnt/β-Catenin Signaling Pathway by Human Papillomavirus E6 and E7 Oncoproteins

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    Jesus Omar Muñoz Bello

    2015-08-01

    Full Text Available Cell signaling pathways are the mechanisms by which cells transduce external stimuli, which control the transcription of genes, to regulate diverse biological effects. In cancer, distinct signaling pathways, such as the Wnt/β-catenin pathway, have been implicated in the deregulation of critical molecular processes that affect cell proliferation and differentiation. For example, changes in β-catenin localization have been identified in Human Papillomavirus (HPV-related cancers as the lesion progresses. Specifically, β-catenin relocates from the membrane/cytoplasm to the nucleus, suggesting that this transcription regulator participates in cervical carcinogenesis. The E6 and E7 oncoproteins are responsible for the transforming activity of HPV, and some studies have implicated these viral oncoproteins in the regulation of the Wnt/β-catenin pathway. Nevertheless, new interactions of HPV oncoproteins with cellular proteins are emerging, and the study of the biological effects of such interactions will help to understand HPV-related carcinogenesis. Viruses 2015, 7 4735 This review addresses the accumulated evidence of the involvement of the HPV E6 and E7 oncoproteins in the activation of the Wnt/β-catenin pathway.

  15. Curcumin promotes the apoptosis of human endometrial carcinoma cells by downregulating the expression of androgen receptor through Wnt signal pathway.

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    Feng, W; Yang, C X; Zhang, L; Fang, Y; Yan, M

    2014-01-01

    The current study aimed to explore the effect ofcurcumin on androgen receptor (AR) expression in endometrial carcinoma cells, as well as the underlying mechanisms. Endometrial carcinoma cells were treated with curcumin (10, 50, and 100 micromol/l) for 12, 24, and 48 hours. Their growth curves were drawn using MTT assays and their apoptotic rates were determined using flow cytometry. The mRNA and protein expression of AR was detected using PCR and that of the Wnt signal related nucleopro- tein beta-cantenin was observed using western blot analysis. The influence of beta-cantenin on the action of curcumin was observed. Curcumin downregulated the proliferation and apoptosis of human endometrial carcinoma cells in concentration and time-dependent manners. It downregulated the expression of AR and beta-cantenin in the cells. rWnt3a partially cancelled the effects of curcumin on the proliferation and apoptosis of human endometrial carcinoma cells as well as the AR expression-downregulating effect of curcumin. Curcumin inhibits the proliferation and apoptosis of human endometrial carcinoma cells by downregulating their AR expression through the Wnt signal pathway.

  16. Molecular signalling in hepatocellular carcinoma: Role of and crosstalk among Wnt/β-catenin, Sonic Hedgehog, Notch and Dickkopf-1

    Science.gov (United States)

    Giakoustidis, Alexandros; Giakoustidis, Dimitrios; Mudan, Satvinder; Sklavos, Argyrios; Williams, Roger

    2015-01-01

    Hepatocellular carcinoma is the sixth most common cancer worldwide. In the majority of cases, there is evidence of existing chronic liver disease from a variety of causes including viral hepatitis B and C, alcoholic liver disease and nonalcoholic steatohepatitis. Identification of the signalling pathways used by hepatocellular carcinoma cells to proliferate, invade or metastasize is of paramount importance in the discovery and implementation of successfully targeted therapies. Activation of Wnt/β-catenin, Notch and Hedgehog pathways play a critical role in regulating liver cell proliferation during development and in controlling crucial functions of the adult liver in the initiation and progression of human cancers. β-catenin was identified as a protein interacting with the cell adhesion molecule E-cadherin at the cell-cell junction, and has been shown to be one of the most important mediators of the Wnt signalling pathway in tumourigenesis. Investigations into the role of Dikkopf-1 in hepatocellular carcinoma have demonstrated controversial results, with a decreased expression of Dickkopf-1 and soluble frizzled-related protein in various cancers on one hand, and as a possible negative prognostic indicator of hepatocellular carcinoma on the other. In the present review, the authors focus on the Wnt/β-catenin, Notch and Sonic Hedgehog pathways, and their interaction with Dikkopf-1 in hepatocellular carcinoma. PMID:25965442

  17. The mTOR and canonical Wnt signaling pathways mediate the mnemonic effects of progesterone in the dorsal hippocampus.

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    Fortress, Ashley M; Heisler, John D; Frick, Karyn M

    2015-05-01

    Although much is known about the neural mechanisms responsible for the mnemonic effects of 17β-estradiol (E2 ), very little is understood about the mechanisms through which progesterone (P4 ) regulates memory. We previously showed that intrahippocampal infusion of P4 in ovariectomized female mice enhances object recognition (OR) memory consolidation in a manner dependent on activation of dorsal hippocampal ERK and mTOR signaling. However, the role of specific progesterone receptors (PRs) in mediating the effects of progesterone on memory consolidation and hippocampal cell signaling are unknown. Therefore, the goals of this study were to investigate the roles of membrane-associated and intracellular PRs in mediating hippocampal memory consolidation, and identify downstream cell signaling pathways activated by PRs. Membrane-associated PRs were targeted using bovine serum albumin-conjugated progesterone (BSA-P), and intracellular PRs (PR-A, PR-B) were targeted using the intracellular PR agonist R5020. Immediately after OR training, ovariectomized mice received bilateral dorsal hippocampal infusion of vehicle, P4 , BSA-P, or R5020. OR memory consolidation was enhanced by P4 , BSA-P, and R5020. However, only P4 and BSA-P activated ERK and mTOR signaling. Furthermore, dorsal hippocampal infusion of the ERK inhibitor U0126 blocked the memory-enhancing effects of BSA-P, but not R5020. The intracellular PR antagonist RU486 blocked the memory-enhancing effects of R5020, but not BSA-P. Interestingly, P4 robustly activated canonical Wnt signaling in the dorsal hippocampus, which is consistent with our recent findings that canonical Wnt signaling is necessary for OR memory consolidation. R5020, but not BSA-P, also elicited a modest increase in canonical Wnt signaling. Collectively, these data suggest that activation of ERK signaling is necessary for membrane-associated PRs to enhance OR, and indicate a role for canonical Wnt signaling in the memory-enhancing effects of

  18. Wnt/Wingless signaling through β-catenin requires the function of both LRP/Arrow and frizzled classes of receptors

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    Varmus Harold

    2003-05-01

    Full Text Available Abstract Background Wnt/Wingless (Wg signals are transduced by seven-transmembrane Frizzleds (Fzs and the single-transmembrane LDL-receptor-related proteins 5 or 6 (LRP5/6 or Arrow. The aminotermini of LRP and Fz were reported to associate only in the presence of Wnt, implying that Wnt ligands form a trimeric complex with two different receptors. However, it was recently reported that LRPs activate the Wnt/β-catenin pathway by binding to Axin in a Dishevelled – independent manner, while Fzs transduce Wnt signals through Dishevelled to stabilize β-catenin. Thus, it is possible that Wnt proteins form separate complexes with Fzs and LRPs, transducing Wnt signals separately, but converging downstream in the Wnt/β-catenin pathway. The question then arises whether both receptors are absolutely required to transduce Wnt signals. Results We have established a sensitive luciferase reporter assay in Drosophila S2 cells to determine the level of Wg – stimulated signaling. We demonstrate here that Wg can synergize with DFz2 and function cooperatively with LRP to activate the β-catenin/Armadillo signaling pathway. Double-strand RNA interference that disrupts the synthesis of either receptor type dramatically impairs Wg signaling activity. Importantly, the pronounced synergistic effect of adding Wg and DFz2 is dependent on Arrow and Dishevelled. The synergy requires the cysteine-rich extracellular domain of DFz2, but not its carboxyterminus. Finally, mammalian LRP6 and its activated forms, which lack most of the extracellular domain of the protein, can activate the Wg signaling pathway and cooperate with Wg and DFz2 in S2 cells. We also show that the aminoterminus of LRP/Arr is required for the synergy between Wg and DFz2. Conclusion Our study indicates that Wg signal transduction in S2 cells depends on the function of both LRPs and DFz2, and the results are consistent with the proposal that Wnt/Wg signals through the aminoterminal domains of its dual

  19. Cross-regulation of signaling pathways: An example of nuclear hormone receptors and the canonical Wnt pathway

    Energy Technology Data Exchange (ETDEWEB)

    Beildeck, Marcy E. [Lombardi Comprehensive Cancer Center, Georgetown University, 3970 Reservoir Road, NW, Washington, DC 20057 (United States); Gelmann, Edward P. [Columbia University, Department of Medicine, New York, NY (United States); Byers, Stephen W., E-mail: byerss@georgetown.edu [Lombardi Comprehensive Cancer Center, Georgetown University, 3970 Reservoir Road, NW, Washington, DC 20057 (United States)

    2010-07-01

    Predicting the potential physiological outcome(s) of any given molecular pathway is complex because of cross-talk with other pathways. This is particularly evident in the case of the nuclear hormone receptor and canonical Wnt pathways, which regulate cell growth and proliferation, differentiation, apoptosis, and metastatic potential in numerous tissues. These pathways are known to intersect at many levels: in the intracellular space, at the membrane, in the cytoplasm, and within the nucleus. The outcomes of these interactions are important in the control of stem cell differentiation and maintenance, feedback loops, and regulating oncogenic potential. The aim of this review is to demonstrate the importance of considering pathway cross-talk when predicting functional outcomes of signaling, using nuclear hormone receptor/canonical Wnt pathway cross-talk as an example.

  20. β-catenin-independent WNT signaling and Ki67 in contrast to the estrogen receptor status are prognostic and associated with poor prognosis in breast cancer liver metastases.

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    Bleckmann, Annalen; Conradi, Lena-Christin; Menck, Kerstin; Schmick, Nadine Annette; Schubert, Antonia; Rietkötter, Eva; Arackal, Jetcy; Middel, Peter; Schambony, Alexandra; Liersch, Torsten; Homayounfar, Kia; Beißbarth, Tim; Klemm, Florian; Binder, Claudia; Pukrop, Tobias

    2016-04-01

    Liver metastasis development in breast cancer patients is common and confers a poor prognosis. So far, the prognostic significance of surgical resection and clinical relevance of biomarker analysis in metastatic tissue have barely been investigated. We previously demonstrated an impact of WNT signaling in breast cancer brain metastasis. This study aimed to investigate the value of established prognostic markers and WNT signaling components in liver metastases. Overall N = 34 breast cancer liver metastases (with matched primaries in 19/34 cases) were included in this retrospective study. Primaries and metastatic samples were analyzed for their expression of the estrogen (ER) and progesterone receptor, HER-2, Ki67, and various WNT signaling-components by immunohistochemistry. Furthermore, β-catenin-dependent and -independent WNT scores were generated and analyzed for their prognostic value. Additionally, the influence of the alternative WNT receptor ROR on signaling and invasiveness was analyzed in vitro. ER positivity (HR 0.09, 95 % CI 0.01-0.56) and high Ki67 (HR 3.68, 95 % CI 1.12-12.06) in the primaries had prognostic impact. However, only Ki67 remained prognostic in the metastatic tissue (HR 2.46, 95 % CI 1.11-5.44). Additionally, the β-catenin-independent WNT score correlated with reduced overall survival only in the metastasized situation (HR 2.19, 95 % CI 1.02-4.69, p = 0.0391). This is in line with the in vitro results of the alternative WNT receptors ROR1 and ROR2, which foster invasion. In breast cancer, the value of prognostic markers established in primary tumors cannot directly be translated to metastases. Our results revealed β-catenin-independent WNT signaling to be associated with poor prognosis in patients with breast cancer liver metastasis.

  1. Shizukaol D, a Dimeric Sesquiterpene Isolated from Chloranthus serratus, Represses the Growth of Human Liver Cancer Cells by Modulating Wnt Signalling Pathway.

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    Tang, Lisha; Zhu, Hengrui; Yang, Xianmei; Xie, Fang; Peng, Jingtao; Jiang, Deke; Xie, Jun; Qi, Meiyan; Yu, Long

    2016-01-01

    Natural products have become sources of developing new drugs for the treatment of cancer. To seek candidate compounds that inhibit the growth of liver cancer, components of Chloranthus serratus were tested. Here, we report that shizukaol D, a dimeric sesquiterpene from Chloranthus serratus, exerted a growth inhibition effect on liver cancer cells in a dose- and time-dependent manner. We demonstrated that shizukaol D induced cells to undergo apoptosis. More importantly, shizukaol D attenuated Wnt signalling and reduced the expression of endogenous Wnt target genes, which resulted in decreased expression of β-catenin. Collectively, this study demonstrated that shizukaol D inhibited the growth of liver cancer cells by modulating Wnt pathway.

  2. Direct Targeting of β-Catenin by a Small Molecule Stimulates Proteasomal Degradation and Suppresses Oncogenic Wnt/β-Catenin Signaling

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    So-Young Hwang

    2016-06-01

    Full Text Available The Wnt/β-catenin signaling pathway plays a major role in tissue homeostasis, and its dysregulation can lead to various human diseases. Aberrant activation of β-catenin is oncogenic and is a critical driver in the development and progression of human cancers. Despite the significant potential of targeting the oncogenic β-catenin pathway for cancer therapy, the development of specific inhibitors remains insufficient. Using a T cell factor (TCF-dependent luciferase-reporter system, we screened for small-molecule compounds that act against Wnt/β-catenin signaling and identified MSAB (methyl 3-{[(4-methylphenylsulfonyl]amino}benzoate as a selective inhibitor of Wnt/β-catenin signaling. MSAB shows potent anti-tumor effects selectively on Wnt-dependent cancer cells in vitro and in mouse cancer models. MSAB binds to β-catenin, promoting its degradation, and specifically downregulates Wnt/β-catenin target genes. Our findings might represent an effective therapeutic strategy for cancers addicted to the Wnt/β-catenin signaling pathway.

  3. Slit2/Robo1 signaling promotes intestinal tumorigenesis through Src-mediated activation of the Wnt/β-catenin pathway.

    Science.gov (United States)

    Zhang, Qian-Qian; Zhou, Da-Lei; Lei, Yan; Zheng, Li; Chen, Sheng-Xia; Gou, Hong-Ju; Gu, Qu-Liang; He, Xiao-Dong; Lan, Tian; Qi, Cui-Ling; Li, Jiang-Chao; Ding, Yan-Qing; Qiao, Liang; Wang, Li-Jing

    2015-02-20

    Slit2 is often overexpressed in cancers. Slit2 is a secreted protein that binds to Roundabout (Robo) receptors to regulate cell growth and migration. Here, we employed several complementary mouse models of intestinal cancers, including the Slit2 transgenic mice, the ApcMin/+ spontaneous intestinal adenoma mouse model, and the DMH/DSS-induced colorectal carcinoma model to clarify function of Slit2/Robo1 signaling in intestinal tumorigenesis. We showed that Slit2 and Robo1 are overexpressed in intestinal tumors and may contribute to tumor generation. The Slit2/Robo1 signaling can induce precancerous lesions of the intestine and tumor progression. Ectopic expression of Slit2 activated Slit2/Robo1 signaling and promoted tumorigenesis and tumor growth. This was mediated in part through activation of the Src signaling, which then down-regulated E-cadherin, thereby activating Wnt/β-catenin signaling. Thus, Slit2/Robo1 signaling is oncogenic in intestinal tumorigenesis.

  4. An LRP5 receptor with internal deletion in hyperparathyroid tumors with implications for deregulated WNT/beta-catenin signaling.

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    Peyman Björklund

    2007-11-01

    Full Text Available BACKGROUND: Hyperparathyroidism (HPT is a common endocrine disorder with incompletely understood etiology, characterized by enlarged hyperactive parathyroid glands and increased serum concentrations of parathyroid hormone and ionized calcium. We have recently reported activation of the Wnt signaling pathway by accumulation of beta-catenin in all analyzed parathyroid tumors from patients with primary HPT (pHPT and in hyperplastic parathyroid glands from patients with uremia secondary to HPT (sHPT. Mechanisms that may account for this activation have not been identified, except for a few cases of beta-catenin (CTNNB1 stabilizing mutation in pHPT tumors. METHODS AND FINDINGS: Reverse transcription PCR and Western blot analysis showed expression of an aberrantly spliced internally truncated WNT coreceptor low-density lipoprotein receptor-related protein 5 (LRP5 in 32 out of 37 pHPT tumors (86% and 20 out of 20 sHPT tumors (100%. Stabilizing mutation of CTNNB1 and expression of the internally truncated LRP5 receptor was mutually exclusive. Expression of the truncated LRP5 receptor was required to maintain the nonphosphorylated active beta-catenin level, transcription activity of beta-catenin, MYC expression, parathyroid cell growth in vitro, and parathyroid tumor growth in a xenograft severe combined immunodeficiency (SCID mouse model. WNT3 ligand and the internally truncated LRP5 receptor strongly activated transcription, and the internally truncated LRP5 receptor was insensitive to inhibition by DKK1. CONCLUSIONS: The internally truncated LRP5 receptor is strongly implicated in deregulated activation of the WNT/beta-catenin signaling pathway in hyperparathyroid tumors, and presents a potential target for therapeutic intervention.

  5. Evidence for involvement of Wnt signalling in body polarities, cell proliferation, and the neuro-sensory system in an adult ctenophore.

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    Muriel Jager

    Full Text Available Signalling through the Wnt family of secreted proteins originated in a common metazoan ancestor and greatly influenced the evolution of animal body plans. In bilaterians, Wnt signalling plays multiple fundamental roles during embryonic development and in adult tissues, notably in axial patterning, neural development and stem cell regulation. Studies in various cnidarian species have particularly highlighted the evolutionarily conserved role of the Wnt/β-catenin pathway in specification and patterning of the primary embryonic axis. However in another key non-bilaterian phylum, Ctenophora, Wnts are not involved in early establishment of the body axis during embryogenesis. We analysed the expression in the adult of the ctenophore Pleurobrachia pileus of 11 orthologues of Wnt signalling genes including all ctenophore Wnt ligands and Fz receptors and several members of the intracellular β-catenin pathway machinery. All genes are strongly expressed around the mouth margin at the oral pole, evoking the Wnt oral centre of cnidarians. This observation is consistent with primary axis polarisation by the Wnts being a universal metazoan feature, secondarily lost in ctenophores during early development but retained in the adult. In addition, local expression of Wnt signalling genes was seen in various anatomical structures of the body including in the locomotory comb rows, where their complex deployment suggests control by the Wnts of local comb polarity. Other important contexts of Wnt involvement which probably evolved before the ctenophore/cnidarian/bilaterian split include proliferating stem cells and progenitors irrespective of cell types, and developing as well as differentiated neuro-sensory structures.

  6. Transient Inhibition of FGFR2b-ligands signaling leads to irreversible loss of cellular β-catenin organization and signaling in AER during mouse limb development.

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    Soula Danopoulos

    Full Text Available The vertebrate limbs develop through coordinated series of inductive, growth and patterning events. Fibroblast Growth Factor receptor 2b (FGFR2b signaling controls the induction of the Apical Ectodermal Ridge (AER but its putative roles in limb outgrowth and patterning, as well as in AER morphology and cell behavior have remained unclear. We have investigated these roles through graded and reversible expression of soluble dominant-negative FGFR2b molecules at various times during mouse limb development, using a doxycycline/transactivator/tet(O-respo