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1
Lundeen, Berent. "Wnt Signaling in Human Cancers : Role of the Wnt receptor FZD9 in Myelopoiesis." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC319.
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Mon travail a été d'étudier le rôle de l'expression de FZD9, un récepteur Wnt, dans l'hématopoïèse normale et maligne. Frizzled 9 (FZD9) est un composant clé de la voie de signalisation Wnt, une voie connue pour jouer un rôle important dans l'hématopoïèse normale et maligne. La méthylation d'un site CpG proximal de site d'initiation de la transcription du gène FZD9 est un facteur de mauvais pronostic dans les LAMs et sa déméthylation est un facteur prédictif de réponse aux thérapies épigénétiques. Sa fonction dans l'hématopoïèse n'est cependant pas connue. Au cours de ma thèse, j'ai démontré que le promoteur du gène FZD9 est dans un état non-permissif dans les cellules leucémiques. L'induction de la différenciation des cellules leucémiques restaure l'état permissif du promoteur, le recrutement du facteur E2F et de l'histone H3 acétyle permettant l'expression de FZD9. L'expression de FZD9 expression est également retrouvée au cours de la différenciation myéloïde d'une lignée IPS Dans les cellules de la lignée THP1 différenciées en monocytes, FZD9 est retrouvé dans un complexe comprenant LRP5/6 et Wnt5a. L'incubation des cellules différenciées par Wnt5a, un ligand de FZD9, déclenche la diminution de l'expression de -caténine et sa localisation nucléaire ainsi que l'expression des gènes cibles de la voie Wnt canonique (c-myc, Cyclin Dl and CD44). Nous n'avons détecté aucune augmentation des taux intracellulaires de calcium. Ces travaux suggèrent que la méthylation du promoteur de FZD9 dans les LAMs pourrait participer à la leucémogénèse en maintenant la voie b-caténine activeMy goal was to study the importance of the expression of the FZD9, a Wnt receptor, in both normal and malignant hematopoiesis. Frizzled 9 (FZD9) is a key component of the Wnt signaling pathway, a pathway which has been shown to play a role in both normal and malignant hematopoiesis. Methylation of the CpG proximal to the transcription start site of the FZD9 gene is recognized as a prognostic factor in AML and its demethylation is a predictive factor for response to epigenetic therapy. Its function in hematopoiesis is however not known. The results show that the FZD9 promoter is in a non-permissive state in leukemic cells. Induction of myeloid differentiation in human myeloid leukemic cell fines restores FZD9 promoter permissiveness with recruitment of E2F and acetylated histone H3 and upregulation of FZD9 mRNA expression. FZD9 expression was progressively increased through the stages of myeloid differentiation in an IPS cell line. In differentiated monocytic THP1 cells, FZD9 was found in the LRPS/6 Wnt receptor complex. Incubation of differentiated cells with Wnt5a, a ligand of FZD9, triggered the decreased expression of - catenin and its nuclear localisation and the canonical Wnt-target genes (c-myc, Cyclin D1 and CD44). We detected no increase in calcium intracellular levels and thus activation of classical non-canonical pathway was not noted upon WntSa incubation. The results of my PhD suggest that the reported methylation of FZD9 promoter in AML and HR-MDS patients may participate in leukemogenesis by the maintenance of an activated Wnt canonical pathway
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Nambiar, Roopa. "Zebrafish hdac1 reciprocally regulates the canonical and non-canonical Wnt pathways." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150313622.
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Child, Nicholas Mark. "Wnt signalling and cardiac development." Thesis, University of Newcastle upon Tyne, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548030.
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Schans, Veerle Anna Maria van de. "Wnt signaling and cardiac hypertrophy." [Maastricht] : Maastricht : [Maastricht University] ; University Library, Universiteit Maastricht [host], 2009. http://arno.unimaas.nl/show.cgi?fid=14684.
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Richards, Alexander S. K. "Wnt Signalling in Malignant Mesothelioma." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/56433.
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The aims of this thesis were to characterise the Wnt signalling system and its pharmacological modulation in mesothelioma derived cell lines using monolayer and three dimensional culture models. Investigations into the effects upon expression of Wnt signal components were performed by inhibiting tankyrase enzymes with the compound XAV939 and histone deacetylase enzymes with suberoylanilide hydroxamic acid. Measurement of effects was carried out using functional assays and RNA sequencing for differential gene expression.
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Eubelen, Marie. "Mécanisme moléculaire de la voie Wnt/β-caténine Gpr124/Reck-dépendante." Doctoral thesis, Universite Libre de Bruxelles, 2019. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/280768.
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La voie Wnt est une voie de signalisation importante pour l’embryogenèse, la morphogenèse et l’homéostasie des tissus au stade adulte. Des mutations dans cette voie de signalisation sont souvent associées à une létalité embryonnaire ou à des pathologies sévères.Une caractéristique singulière de la signalisation Wnt est sa grande complexité génétique. Chez les vertébrés, ce sont 19 ligands Wnt différents qui peuvent potentiellement lier les 10 membres de la famille des récepteurs Frizzled (Fz). De plus, la liaison d’un ligand Wnt à un récepteur Fz peut conduire à l’activation d’au moins trois voies de transduction distinctes. Pourtant, l’interaction Wnt/Fz est incompatible avec une reconnaissance monospécifique étant donné que Wnt et Fz interagissent via des résidus conservés dans les deux familles. Les patrons d’expression des différents Wnt et des différents Fz sont complexes et souvent chevauchant. Malgré cela, la délétion sélective d’un Wnt peut conduire à des phénotypes spécifiques non-observés lors de la délétion d’un autre ligand Wnt co-exprimé. C’est notamment le cas des ligands Wnt7a et Wnt7b. Seules leurs expressions par les progéniteurs neuronaux permettent d’activer la voie de signalisation Wnt/β-caténine dans les cellules endothéliales malgré l’expression simultanée d’autres ligands Wnt. Dès lors, comment les cellules des vertébrés sont-elles capables de discriminer les différents ligands Wnt ?L’étude de l’activation des signalisations induites par les ligands Wnt7a et Wnt7b permet d’illustrer par quel mécanisme moléculaire des co-récepteurs, tels que Gpr124 et Reck, médient la reconnaissance spécifique d’un ligand Wnt et permettent la formation d’un signalosome spécifique. Reck est un récepteur spécifique des ligands Wnt7a et Wnt7b qui permet de les discriminer de tous les autres ligands Wnt. Il interagit avec ceux-ci via une région intrinsèquement désordonnée et divergente dans la famille Wnt appelée « le peptide linker ». Etant donné que cette région est exposée au solvant et qu’elle ne comprend pas les sites d’interaction avec le récepteur Fz, elle pourrait jouer un rôle critique dans la discrimination des différents ligands Wnt. Gpr124, quant à lui, interagit avec Reck via son domaine extracellulaire et permet la co-localisation de ce dernier et des récepteurs Fz dans le même signalosome. Pour ce faire, Gpr124 interagit avec la protéine adaptatrice Dvl via son domaine intracellulaire. Le recrutement membranaire et la polymérisation de Dvl permettent la formation d’une plateforme d’ancrage facilitant la formation du complexe Reck/Gpr124/Fz/Lrp5/6 qui active alors sélectivement la voie la signalisation Wnt/β-caténine en réponse aux ligands Wnt7a et Wnt7b. L’identification d’un tel mécanisme de décodage laisse supposer qu’il pourrait exister plusieurs modules de reconnaissance spécifique adaptés à d’autres ligands Wnt assurant ainsi un réglage précis de la signalisation Wnt en fonction du contexte moléculaire de la membrane plasmique.Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Asbrand, Christian. "Neue Mechanismen der Regulation von Conductin im Wnt-ss-Catenin-Signalweg [Wnt-beta-Catenin-Signalweg]." [S.l.] : [s.n.], 2002. http://www.diss.fu-berlin.de/2002/130/index.html.
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Ng, Chun-laam, and 吳圳嵐. "Wnt inhibitory factor 1 (Wif-1) coordinates Shh and Wnt signaling activities in urorectal development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329629.
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In vertebrates, the urogenital sinus and the hindgut are connected at a hollow region called cloaca. A midline mesenchymal structure known as urorectal septum (urs) descends from the ventral body wall to separate the urogenital sinus from the hindgut before the formation of an anal opening. Subsequent cloaca membrane regression at the ventral midline of the genital tubercle (GT) is crucial for the formation of an anal opening. These two events are important during cloaca septation in urorectal development.
Mice with defective Shh or Wnt signaling displayed similar urorectal defects such as GT agenesis, un-partitioned cloaca (persistent cloaca) and proximal urethral opening that are attributable to increased cell apoptosis. Furthermore, Shh and Wnt signal transduction coordinate with each other and regulate cell survival of the developing urorectum. However, the molecular mechanisms by which these two signaling pathways coordinate in urorectal development remain unclear.
We previously identified Wnt inhibitory factor1 (Wif1) from Affymetrix array analysis for genes/pathways that is implicated in urorectal development. Wif1 is a secreted protein that binds directly to Wnt ligands preventing Wnts from binding to receptors. This leads to -catenin degradation and thereby inhibits their activities. It is known that Wif1 binds to Wnt3a and Wnt5a with high affinity and deletion of Wnt3a, Wnt5a and -catenin in mice caused GT agenesis, persistent cloaca and proximal hypospadias. Using ETU-induced anorectal malformations model, I found out that Wif1 is ectopically expressed in the un-tubularized and un-septated urorectum. Wif1 is mainly expressed at the fusing endoderm that associates with programmed cell death during cloaca septation. Exogenous addition of Wif1 protein in urorectum culture also caused cloaca membrane disintegration, and proximal urethral opening that may be due to aberrant apoptosis.
Shh and Wif1 are differentially expressed at the cloaca endoderm. In normal mice, Shh is highly expressed at the cloaca endoderm except those Wif1-expressing endodermal cells. Blockage of Shh pathway by cyclopamine in urorectum culture induced ectopic expression of Wif1, concomitant with genital tubercle hypoplasia and un-septated cloaca. More importantly, deletion of Shh in mice hastened Wif1 expression at the cloaca membrane endoderm and elicited increased cell death in the
Wif1 expressing endoderm. Wif1-/- embryos display urorectal defects including delayed genital outgrowth and proximal hypospadias. Therefore, disruption of spatiotemporal expression of Wif1 could lead to defective Wnt signaling and contributes to abnormal urorectal development in Shh-/- mutant.
Current study revealed that Wif1 is involved in urorectal development and is implicated in urorectal defects. It may function as a pro-apoptotic factor to regulate endodermal cell death which is essential for the septation process. Its specific expression is restricted at the midline cloaca endoderm by Shh signaling to inhibit local Wnt--catenin activities during cloaca septation. I proposed novel hypothetical models to explain (1) the significance of the tempo-spatial expression of Wif1; (2) the significance of cell death; and (3) the molecular mechanism that Shh signaling regulates Wnt signaling activities through Wif1 in urorectal development.published_or_final_version
Surgery
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Doctor of Philosophy
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Chow, Hei-man, and 周熙文. "Hormonal, chemical, and transcriptional regulations of Wnt/{221}-catenin signaling in mammary carcinogensis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B4589100X.
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Railo, A. (Antti). "Wnt-11 signalling, its role in cardiogenesis and identification of Wnt/β-catenin pathway target genes." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261534.
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Abstract
Wnt genes encode secreted signalling molecules that control embryonic development including organogenesis, while dysregulated Wnt signalling is connected to many diseases such as cancer. Specifically, Wnts control a number of cellular processes such as proliferation, adhesion, differentiation and aging. Many Wnt proteins activate the canonical β-catenin signalling pathway that regulates transcription of a still poorly characterized set of target genes. Wnts also transduce their signaling in cells via β-catenin-independent “non-canonical” pathways, which are not well understood. In this study, Wnt-11 signalling mechanisms in a mammalian model cell line and roles of Wnt-11 in heart development were analyzed in detail. In addition the aim was to identify new Wnt target genes by direct chromatin immunoprecipitation and Affymetrix GeneChip assays in the model cells exposed to Wnt-3a.
Our studies reveal that Wnt-11 signalling coordinates the activity of key cell signalling pathways, namely the canonical Wnt/β-catenin, the JNK/AP-1, the NF-κB and PI3K/Akt pathways in the CHO cells. Analysis of the Wnt-11-deficient embryos revealed a crucial role in heart organogenesis. Wnt-11 signalling coordinates cell interactions during assembly of the myocardial wall and Wnt-11 localizes the expression of N-cadherin and β-catenin to specific cellular domains in the embryonic ventricular cardiomyocytes. Collectively these studies reveal that the mammalian Wnt-11 behaves as a non-canonical Wnt and that it is a critical factor in the coordination of heart development. Specifically, it controls components of the cell adhesion machinery. Analysis of the Wnt target genes revealed a highly context-dependent profile in the Wnt-regulated genes. Several new putative target genes were discovered. Out of the candidate Wnt target genes, Disabled-2 was identified as a potential new direct target for Wnt signalling.
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Komekado, Hideyuki. "Glycosylation and palmitoylation of Wnt-3a are coupled to produce an active form of Wnt-3a." Kyoto University, 2007. http://hdl.handle.net/2433/135740.
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Schwarcz, Leslie Esther. "Linking steroid hormone and Wnt signaling /." view abstract or download file of text, 2006. http://wwwlib.umi.com/cr/uoregon/fullcit?p3211226.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 71-82). Also available for download via the World Wide Web; free to University of Oregon users.
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Agholme, Fredrik. "Wnt signaling and metaphyseal bone healing." Doctoral thesis, Linköpings universitet, Ortopedi och idrottsmedicin, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71287.
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This thesis relates to some new aspects on the regulation of bone healing. In the last few years, Wnt-signaling has been shown to play a central role in bone biology. As well as being involved in bone maintenance and repair, Wnt-signaling has been presented as one of the key pathways through which bone responds to mechanical load. Two secreted extracellular inhibitors of Wnt-signaling, sclerostin and dickkopf-1 are potent negative regulators of bone formation. Using a rat fracture model we investigated how metaphyseal bone healing is influenced by changes in Wnt-signaling. Antibodies were used to suppress levels of sclerostin and dickkopf-1, and thereby increase Wnt-signaling. Primarily, we investigated if those antibody treatments lead to improved bone healing. Also, we investigated if the response was coupled to the loading conditions of the bone. Our findings suggest that suppression of either sclerostin or dickkopf-1 leads to increased bone formation and improved bone healing. Apart from just having an effect on healing, the treatment also improved bone formation in other parts of the skeleton. Depending on the loading conditions, the effects were different. Dickkopf-1 appeared to have a stronger effect on bone volume density in unloaded bone, implying a role mainly in mechano-transduction, while sclerostin had similar effect in both loaded and unloaded bone. To confirm these findings, we studied how the expression of several Wnt-related genes changed due to trauma and unloading in metaphyseal bone. We found that trauma led to upregulation of most of the genes with the largest effect seen in the unloaded bone. In untraumatized bone, there was mainly an effect on the sclerostin gene. In conclusion, antibodies against sclerostin and dickkopf-1 appear to be able to improve metaphyseal bone healing. There appear to be some differences in how the effect of the two antibodies manifests itself, especially if the loading conditions of the bone are altered. These findings suggest a potential for clinical use to shorten fracture healing time.
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Gardner, Samantha. "Gonadotropin-releasing hormone targets Wnt signalling." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/29112.
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This thesis describes a potential mechanism by which GnRH promotes the nuclear accumulation of β-catenin, activation of TCF-dependent transcription and up-regulation of Wnt target genes, c-Jun, Fra-1, Cyclin D1 and c-Mye. GnRH-induced nuclear accumulation of β-catenin and activation of β-catenin/TCF-dependent transcription was found to be dependent on a pathway utilising Gq-Phospholipase C (PLC)-Diacylglycerol (DAG)/Protein kinase C (PKC), and was found to be specifically dependent on the PKC δ isoform. GnRH was found to mediate the inactivation of Glycogen Synthase Kinase-3 (GSK-3), a protein serine/threonine kinase that regulates β-catenin degradation within the canonical Wnt signalling pathway. These results were observed in HEK293/GnRH receptor expressing cells and have been recapitulated in LβT2 and αT3-1 mouse gonadotrope cells, and then extended to various peripheral cell lines, sub-cultured prostate cells and whole prostate organ cultures. A potential mechanism of non-canonical Wnt/Ca2+ pathway activation by GnRH is described. GnRH was found to activate NFAT, a potential effecter of the non-canonical Wnt/Ca2+ pathway. GnRH-induced NFAT activation was found to be dependent on important mediators of the non-classical Wnt/Ca2+ pathway, including Gq, Ca2+, Calcineurin and PKC δ. Intriguingly, by expression of a dominant negative TCF construct, GnRH-induced NFAT activation was found to be TCF-dependent, thereby implicating TCF in targeting both Wnt/β-catenin and Wnt/Ca2+ signalling. This novel finding suggests that a TCF-NFAT interaction may exist that functions either, to inhibit β-catenin/TCF-dependent transcription through competition for nuclear TCF, or to synergistically regulate TCF- and NFAT-target gene expression.
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Huguet, Emmanuel L. "Wnt genes in human breast biology." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297228.
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Chen, Demeng. "WNT SIGNALING AND HAIR FOLLICLE INITIATION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1355448596.
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Torres, Monica Alexandra. "WNT signaling pathways in Xenopus laevis /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6293.
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Baumann, Fabrizio. "Cell signalling through the Wnt pathway /." [S.l.] : [s.n.], 2004. http://www.zb.unibe.ch/download/eldiss/04baumann_f.pdf.
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Mellin, Ronan Peter. "Investigating the function of VANGL2 in intestinal homeostasis & disease." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31186.
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Introduction: Van Gogh-Like 2 (VANGL2) is a scaffolding planar cell polarity protein involved in non-canonical Wnt signalling. It has been shown to have crucial roles in regulating epithelial development and homeostasis. Moreover, VANGL2 has been implicated in human cancers, with increased expression and copy number amplification seen in several cancer contexts. Many related components within this pathway have also been linked to cancer development, with VANGL2 expression known to regulate factors involved in cell migration and extracellular matrix (ECM) remodelling in cell lines. These cellular processes tend to be erroneously activated in cancer. VANGL2 is known to inhibit the classical driver pathway of colorectal cancer (CRC), canonical, or β- catenin dependant, Wnt signalling, in CRC cell lines. The aim of this thesis is to determine the expression of VANGL2 in CRC, and to investigate how VANGL2 may act to regulate intestinal homeostasis and disease. Methods: Transcriptional verification of VANGL2 expression in the mouse intestine was carried out by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR), and transcripts localised within the murine colon using RNA-In Situ Hybridisation (RNAISH). Expression and localisation of the VANGL2 protein and related non-canonical Wnt signalling components was confirmed using immuno-histochemistry (IHC). Furthermore, using a combination of human Tissue Micro-Array (TMA), transcriptional data and genomic data, we determined an association between VANGL2 on tumour grade and disease-free survival. To functionally validate the effects of VANGL2 on colorectal biology, we used a model in which VANGL2 is selectively deleted from the colonic epithelium using Villin-CreERT Vangl2flox mouse lines. Using a combination of molecular biology methods, we identified the ECM as differentially regulated following VANGL2 modulation. To test the role of VANGL2 in colorectal cancer, we used a murine colorectal cancer model in which adenomatous polyposis coli (APC) is deleted from colonic epithelium resulting in the formation of cancer concurrently with deletion of Vangl2. We evaluated survival of these mice as well as tumour number and size. Tumour tissue was analysed using IHC, qRT-PCR and 3-Dimensional organoid culture. Results: Within this thesis I have illustrated that the murine colonic epithelium expresses Vangl2, and other components known to interact with VANGL2 including Vangl1, Wnt5A, and Protein Tyrosine Kinase 7 (Ptk7). I have also shown that VANGL2 is expressed within the human colonic epithelium. I go on to show that 9.2% of human CRC possesses VANGL2 transcriptional alterations which correlates with a worsened disease-free survival (DFS) rate among patients. Using IHC, I also show that higher grade CRC is associated with increased VANGL2 expression. In our murine cancer model, mice with single or dual-copy loss of VANGL2 were found to have a reduced number of colonic tumours, while maintaining similar tumour size. Investigations to identify how VANGL2 may have control of tumour initiation were carried out focussing on the ECM. I found that, contrary to what I have discovered in the healthy murine colon, tumours from VANGL2-deficient mice had increased transcription of the ECM markers Secreted protein acidic and rich in cysteine (Sparc) and Decorin (Dcn), as well as increased expression of the ECM regulators Matrix Metallopeptidase 9 (Mmp9) and Tissue Inhibitor of Metalloproteinases 1 (Timp1). Changes in the ECM was also seen at the protein level, with increases in staining for the ECM components Col1 (Collagen, type I), and Laminin in VANGL2-deficient tissue. The ECM modulator Connective Tissue Growth Factor (Ctgf), is implicated in multiple cancers including CRC and is increased within VANGL2-deficient tumours at both the transcript and protein level, implicating Ctgf in increasing the ECM of these tumours.
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Mailavaram, Sravanthi. "Database for the Study of Biological Pathways, with Wnt Signaling Pathway Use Case." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227118211.
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Witzel, Sabine. "Local Wnt11 Signalling and its role in coordinating cell behaviour in zebrafish embryos." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1162424627109-87779.
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Wnt11 is a key signalling molecule that regulates cell polarity/migration during vertebrate development and also promotes the invasive behaviour of adult cancer cells. It is therefore essential to understand the mechanisms by which Wnt11 signalling regulates cell behaviour. The process of vertebrate gastrulation provides an excellent developmental system to study Wnt11 function in vivo. It is known that Wnt11 mediates coordinated cell migration during gastrulation via the non-canonical Wnt pathway that shares several components with a the planar cell polarity pathway (PCP) in Drosophila. However, the mechanisms by which these PCP components facilitate Wnt11 function in vertebrates is still unclear. While in Drosophila, the asymmetric localization of PCP components is crucial for the establishment of cell polarity, no asymmetric localization of Wnt11 pathway components have so far been observed in vertebrates. To shed light on the cellular and molecular mechanisms underlying Wnt11 signalling, I developed an assay to visualize Wnt11 activity in vivo using live imaging of Wnt11 pathway components tagged to fluorescent proteins. This allowed me to determine the sub-cellular distribution of these components and to correlate the effect of Wnt11 activity with the behaviour of living embryonic cells. I found that Wnt11 locally accumulates together with its receptor Frizzled7 (Fz7) at sites of cell-cell contacts and locally recruits the intra-cellular signalling mediator Dishevelled (Dsh) to those sites. Monitoring these apparent Wnt11 signalling centres through time-lapse confocal microscopy revealed, that Wnt11 activity locally increases the persistency of cell-cell contacts. In addition, I found that the atypical cadherin Flamingo (Fmi) is required for this process. Fmi accumulates together with Wnt11/Fz7 at sites of cell-cell contact and locally increased cell adhesion, via a mechanism that appears to be independent of known downstream effectors of Wnt11 signalling such as RhoA and Rok2. This study indicates that Wnt11 locally interacts with Fmi and Fz7 to control cell-contact persistency and to facilitate coherent and coordinated cell migration. This provides a novel mechanism of non-canonical Wnt signalling in mediating cell behaviour, which is likely relevant to other developmental systems. (Die Druckexemplare enthalten jeweils eine CD-ROM als Anlagenteil: 50 MB: Movies - Nutzung: Referat Informationsvermittlung der SLUB)
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Gessert, Susanne. "Untersuchung potentieller Zielgene des nicht-kanonischen Wnt-Signalwegs." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60607.
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Ho, Sze-hang, and 何思恆. "Differential expression of Wnt inhibitors Dickkopf-1 (Dkk-1) and Wnt inhibitory factor-1 (Wif1) in the regulation of urorectal development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/207999.
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In mammals, the external genitalia, urinary tract and anorectal tract are developed from a common embryonic primordium, the urorectum. Cloaca is the hollow space inside the urorectum that connects the hindgut and the urogenital sinus. During the urorectal development, the external genitalia is formed from the outgrowth of genital tubercle (GT) protruding from the urorectum, while the future urinary tract and anorectal tract are formed by the partition of cloaca during cloacal septation. GT outgrowth and cloacal septation are important developmental events for the formation of genitourinary and anorectal system. In human, dysregulation of these developmental events results in congenital anorectal malformations (ARM).
Wnt signaling is one of the key signaling pathways that regulates urorectal development. The activity of Wnt signaling is initiated by the binding of Wnt ligands to cell surface receptors, which can be antagonized by secretory Wnt inhibitors. Dickkopf1 (Dkk1) and Wnt inhibitory factor 1 (Wif1) are secretory Wnt inhibitors implicated in urorectal development. However, the functions of other secretory Wnt inhibitors during urorectal developments remain to be elucidated.
In this study, expression analyses showed that Dkk1, Dickkopf2 (Dkk2), Dickkopf4 (Dkk4), Secreted Frizzled-related Protein 1 (Sfrp1) and Wif1 were expressed in the developing urorectum. The dynamic, overlapping and restricted expression patterns of these Wnt inhibitors were closely associated with the GT outgrowth and the cloacal septation events, implying that these Wnt inhibitors functioned in a coordinated manner in defining the field of Wnt signaling activities in the developing urorectum.
Wif1 knockout mice (〖Wif1〗^(-/-)) was used as the model to investigate the functions of and the interplay between secretory Wnt inhibitors in urorectal development. GT outgrowth and cloacal septation defects were observed in 〖Wif1〗^(-/-) embryos. Most of the 〖Wif1〗^(-/-) embryos displayed varying degrees of GT outgrowth defects, while septation defects were only occasionally observed. This suggested that GT outgrowth and cloacal septation were regulated by Wif1 via different regulatory mechanisms.
In the urorectum of 〖Wif1〗^(-/-) embryos, Dkk1 was significantly upregulated in the peri-cloacal mesenchyme. Further expression analysis suggested that Dkk1 was sufficient to rescue cloacal septation defects but not GT outgrowth defects in 〖Wif1〗^(-/-)embryos. In the 〖Wif1〗^(-/-) embryos with severe GT outgrowth defects, the Fgf8-expressing distal urethral epithelium, the signaling center in the urorectum, was absent, suggesting that the GT outgrowth defects could be contributed by the loss of dUE-expressing signals such as Fgf8.
This study demonstrated the importance of secretory Wnt inhibitors in the GT outgrowth and cloacal septation and suggested that secretory Wnt inhibitors played partially overlapping roles in urorectal development. A rescue mechanism for cloacal septation performed by Dkk1 upon Wif1 deletion was proposed. Such auto-regulatory mechanism within the Wnt signaling pathway indicated that Wnt inhibitors play essential regulatory roles in the urorectal development and a balanced Wnt signaling activity modulated by Wnt inhibitors is crucial to the development of urorectum.published_or_final_version
Surgery
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Master of Philosophy
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Vinyoles, i. Vergés Meritxell. "Nous reguladors en la via de Wnt." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/284139.
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La via canònica de Wnt és essencial pel desenvolupament embrionari i per la proliferació cel·lular. A més, la desregulació d’aquesta via causa diferents malalties, com per exemple el càncer. La unió del lligand Wnt als receptors específics promou la fosforilació de Dvl-2 per una quinasa directament associada a p120-catenina, la CK1ε, i indueix una cascada d’activació que inhibeix l’activitat de la quinasa GSK-3 sobre la β-catenina. Com a resultat, la β-catenina s’estabilitza i es transloca al nucli on activa l’expressió de gens diana.
Els nostres resultats expliquen com la CK1ε és activada ràpidament en Wnt i permet els diferents esdeveniments que acumulen la β-catenina. Prèviament s’havia descrit que la CK1ε presenta un domini autoregulador que inhibeix l’activitat quinasa de la CK1ε quan aquest està fosforilat, suggerint que es necessita una fosfatasa encara no descrita perquè s’activi la senyalització de Wnt. En aquest treball es mostra que la PP2A permet la defosforilació de la CK1ε en Wnt, i també s’ha identificat la PR61ε com la subunitat reguladora de la PP2A que controla l’activació de CK1ε. A més, la PR61ε interacciona directament amb el receptor Fz i s’associa al complex LRP5/6-p120-catenina-CK1ε després de l’activació de Wnt. En global, aquests resultats suggereixen que la PR61ε regula específicament la defosforilació de la CK1ε mediada per la PP2A, i té un paper essencial en la senyalització de Wnt.
Un altre pas determinant de l’activació de la via de Wnt és la inhibició de l’activitat de la GSK-3, tot i que el mecanisme pel qual s’inactiva la quinasa encara és matèria de debat. S’han proposat dos models per explicar-ho, un dependent del reclutament de la GSK-3 al correceptor LRP5/6 fosforilat, que crea un lloc d’inhibició, i l’altre basat en el segrest de la quinasa dins de cossos multivesiculars (MVBs).
Degut a que el nostre grup ha descobert una connexió directa entre les cadherines i la p120-catenina (dues proteïnes involucrades en les unions adherents) amb el correceptor LRP5/6, es va hipotetitzar que les cadherines podrien estar involucrades en l’endocitosi de la GSK-3 dependent dels factors Wnt.
Els nostres resultats demostren que el complex receptor de Wnt que conté la GSK-3, s’internalitza dins de MVBs, i que aquesta endocitosi depèn de la dissociació prèvia de la p120-catenina-cadherina del correceptor LRP5/6. La disrupció de la interacció cadherina-LRP5/6 és regulada per la fosforilació de la cadherina i requereix de la separació prèvia de la p120-catenina. D’aquesta manera, mutants de la p120-catenina i de la cadherina que no es dissocien del complex bloquegen el segrest de la GSK-3 dins de MVBs. Aquests mutants inhibeixen l’acumulació de β-catenina, tot i que no de forma total.
Aquests resultats expliquen com es segresta la GSK-3 dins dels MVBs i suggereixen que aquest mecanisme d’internalització, juntament amb la inhibició de la GSK-3 per la interacció directa amb l’LRP5/6 fosforilat, són necessaris per la completa estabilització de la β-catenina en Wnt.Canonical Wnt signalling is essential for embryonic development and cell proliferation. Deregulation of this pathway leads to some diseases, such as cancer. Binding of extracellular Wnt ligands to specific receptors induces the phosphorylation of Dvl-2 protein by CK1ε- associated-p120-catenin kinase, and a cascade of events that inhibit the activity of GSK3 kinase on β-catenin. As a result, β-catenin is stabilized and translocated to the nucleus where it activates the expression of target genes. Our results explain how CK1ε is quickly activated in Wnt signalling, allowing the cascade of events that accumulate β-catenin. It was previously described that CK1ε presents an autoregulation domain which strongly inhibits CK1ε kinase activity when it is phosphorylated, suggesting that a phosphatase is required to activate Wnt signalling. However, which phosphatase dephosphorylates CK1ε in Wnt and how this phosphatase regulates the pathway were not clear. In this study, we have described that PP2A permits the dephosphorylation of CK1ε upon Wnt, and we have also identified PR61ε as the regulatory subunit of PP2A that controls this CK1ε activation. PR61ε directly interacts with Fz receptor, and associates with LRP5/6-p120-catenin-CK1ε complex upon Wnt activation. Taken together, these results suggest that PR61ε specifically regulates PP2A-mediated CK1ε dephosphorylation and plays an essential role in Wnt signaling. Another key step in the pathway is the local inhibition of GSK3 activity on β-catenin, although the mechanism of this inactivation remains unclear. Two models have been proposed, one dependent on the recruitment and subsequent block of GSK3 by phosphorylated LRP5/6 coreceptor that creates an inhibitory site, and another one based on its sequestration into multivesicular bodies (MVBs). Since our group has uncovered a physical link between cadherins and p120-catenin (two proteins involved in adherens junctions) with the Wnt coreceptor LRP5/6, we wonder whether cadherins may be involved in the endocytosis of GSK3 triggered by Wnt factors. Our results demonstrate that Wnt receptor complexes containing GSK3 are internalized into multivesicular bodies and this endocytosis depends on the previous dissociation of p120-catenin and cadherin from LRP5/6 coreceptor. Thus, disruption of cadherin-LRP5/6 interaction is regulated by cadherin phosphorylation and requires the previous release of p120-catenin. Accordingly, p120-catenin and cadherin mutants unable to dissociate from the complex block GSK3 sequestration into MVBs. These mutants substantially inhibit, but do not completely prevent, the β-catenin accumulation caused by Wnt. These results elucidate how GSK3 is sequestered into MVBs and suggest that this mechanism of internalization together with the inhibition of GSK3 by direct interaction with phosphorylated LRP5/6, are both required for complete β-catenin stabilization upon Wnt stimulation.
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Curto, Navarro Josué. "Initial events in non-canonical Wnt signaling." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/461992.
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La ruta canònica i no canònica de Wnt activen vies de senyalització que generen respostes cel·lulars diferents. Tanmateix, els esdeveniments de senyalització inicials com a resposta a l'estimulació amb els lligands mostren alguns elements comuns. Les dues vies requereixen que el receptor Frizzled (Fz) promogui la fosforilació i el reclutament de Dishevelled al complex de senyalització. En la ruta canònica de Wnt, la CK1ε associada a la p120-catenina s'ha d'activar per permetre la fosforilació i el reclutament de Dvl a Fz. Aquí demostrem que aquestes dues proteïnes també són necessàries per promoure aquest pas en l'estimulació amb Wnt5a. A més, també és necessari el complex format per la PR61ε/PP2A que interacciona amb Fz per activar CK1ε i induir el clúster de receptors. Tanmateix, la dependència d'aquests dos factors és diferent perquè, en la via no canònica Wnt, la p120 no és necessària per a l'associació de la CK1ε amb el coreceptor, ja que ambdues proteïnes interactuen independentment amb Ror2. A més, la interacció de la p120-catenina amb Ror2 depèn de la fosforilació dels seus residus tirosina. Aquesta interacció permet que la p120-catenina estabilitzi Ror2 a la membrana i evita la internalització d'aquest últim mitjançada per clatrina. D'altra banda, la unió de la CK1ε a l'extrem C-terminal controla els nivells totals de proteïna de Ror2 i evita la seva degradació lisosomal. Aquest paper central de la p120-catenina i CK1ε en les etapes de senyalització inicials també és necessari per a respostes més tardanes com la regulació dels nivells de β-catenina a través de Siah2, o per als processos d'invasió cel·lular i la polimerització d'actina cortical. Per tant, els nostres resultats demostren la importància d'aquestes dues proteïnes clau en l'activació de la via de Wnt no canònica.Canonical and non-canonical Wnt pathway have shown to activate signaling pathways that trigger different cellular outputs. However, the initial signaling events upon ligand stimulation show some common elements. The two pathways requires the receptor Frizzled (Fz) to promote Dishevelled phosphorylation and recruitment to the signaling complex. In canonical Wnt pathway, p120-catenin associated CK1ε must be activated to allow Dvl phosphorylation and recruitment to Fz. Here we demonstrate that this two proteins are also required to promote this step upon Wnt5a stimulation. Moreover, Fz associated PR61/PP2A is also necessary to activate CK1 and induce receptor clustering. However, the dependence on these two factors is different, in non-canonical Wnt pathway p120 is not required for CK1ε association to the coreceptor since both proteins independently interact with Ror2. Moreover, p120-catenin associates to Ror2 in a tyrosine phosphorylation-dependent manner. P120-catenin stabilizes Ror2 at the membrane and avoids clathrin-mediated Ror2 internalization. On the other hand, CK1ε binding to the C-terminal part controls Ror2 total levels and prevents its lysosomal degradation. This central role of p120-catenin and CK1ε in the initial signaling events are required for later responses such as Siah2-dependent -catenin downregulation, cell invasion and cortical actin polimerization. Therefore, our results demonstrate the requirement of these two key proteins in the non-canonical Wnt pathway and describe how this pathway is activated.
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Nimmrich, Inko. "Tumorspezifisch exprimierte und Wnt-1-induzierte Gene." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=959806369.
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Schwarz-Romond, Thomas. "Diversin, eine neue Komponente des Wnt-Signalweges." [S.l. : s.n.], 2002. http://www.diss.fu-berlin.de/2003/19/index.html.
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Björklund, Peyman. "Wnt/β-Catenin Signalling in Parathyroid Tumours." Doctoral thesis, Uppsala University, Department of Surgical Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8317.
Full textAbstract:
Primary hyperparathyroidism (pHPT) due to parathyroid tumours with hypersecretion of parathyroid hormone and hypercalcaemia is a common disease with incompletely understood etiology affecting more than 1 % of the population, primarily postmenopausal women. In secondary hyperparathyroidism (sHPT), parathyroid tumours develop in response to calcium and vitamin D deficiency generally in patients with uraemia. HPT is usually treated by surgical removal of enlarged parathyroid glands.
The aim of this thesis was to examine the Wnt/β-catenin signalling pathway in parathyroid tumours.
Aberrantly accumulated β-catenin was found in all analysed pHPT and sHPT tumours, with a stabilising homozygous mutation (Ser37Ala) in 7.3% of the pHPT tumours. Truncation of the APC protein was not found. MYC, a β-catenin target gene was overexpressed in a substantial fraction of pHPT and sHPT parathyroid tumours.
A parathyroid tumour cell line (sHPT-1) was established from a hyperplastic gland removed at operation of a patient with sHPT. The cells produced parathyroid hormone and grew with a doubling time of approximately 72 hours. Stabilised nonphosphorylated transcriptionally active β-catenin was expressed. Efficient transfection of siRNA against β-catenin decreased expression of cyclin D1 and MYC, and inhibited cell growth with ensuring cell death.
The Wnt coreceptor LRP5 was found expressed with an internal deletion of 142 amino acids (LRP5Δ) in 86% and 100% of pHPT and sHPT tumours, respectively. Stabilising mutation of β-catenin and expression of LRP5Δ was mutually exclusive. Expression of LRP5Δ was required to maintain the nonphosphorylated transcriptionally active ß-catenin level, MYC expression, parathyroid cell growth in vitro, and tumour growth in transplanted SCID mice. Wnt3 ligand and LRP5Δ strongly activated transcription, and LRP5Δ was insensitive to inhibition by DKK1.
Aberrant accumulation of β-catenin by stabilising mutation or expression of LRP5Δ appears as a common pathogenic pathway for hyperparathyroid disease. LRP5Δ in particular presents a potential target for therapeutic intervention.
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McLaughlin, David Anthony. "Role of Wnt signalling in forebrain development." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/24959.
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In situ hybridisation (ISH) was used to determine the expression pattern of a new member of the Wnt gene family Wnt8B. During early development Wnt8B expression was observed in the cerebral cortical hem region which is presumptive for the hippocampus. In the adult, Wnt8B is expressed in the dentate gyrus region of the hippocampus, one of the areas in which adult neurogenesis takes place. To investigate the role of Wnt8B in regulating central nervous system development we undertook histological analysis and 5-bromo2-deozyuridine (BrdU) studies in Wnt8B+/+ and Wnt8B-/- mice in regions where Wnt8B is expressed. Surprisingly, histological analysis showed no obvious abnormalities in Wnt8B-/- animals. Further, no significant differences in cell proliferation were found in BrdU studies in the Wnt8B-/- embryos or adult mice. Heparan sulphate proteoglycans are structurally dynamic molecules required for Wnt signalling. The nature of specific structural modifications made to these molecules such as the sulphation pattern is thought to confer specific biological effects. To determine the role of 2-0 sulphation in cellular proliferation in the cerebral cortical hem during development, BrdU studies were undertaken in mice deficient in the enzyme heparan sulphate 2-0 sulphotransferase (Hs2st). BrdU labelling was also used to investigate cell migration in the cerebral cortex and a combination of histochemical techniques was applied to look for gross and subtle anatomical defects in the forebrain of Hs2st-/- mice. In agreement with a dramatically reduced thickness of the cerebral cortex seen in histological sections, BrdU labelling indicated proliferative rates 40% lower in Hs2st-/- mice. Finally, the developmental expression of a member of the Wnt gene receptor family Frizzled-1 was examined using in situ hybridisation with particular emphasis on co-expression with Wnt10B. Frizzled-1 expression was found in the developing tooth, limb and forebrain which coincided with expression of Wnt10B suggesting a possible ligand-receptor relationship.
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Micallef, Rachel Antonia. "Wnt signalling in endocrine resistant breast cancer." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/41274/.
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Wnt signalling components are reported to be deregulated in breast cancer but the contribution of this pathway in endocrine resistance is less clearly defined. Endocrine resistance is an important clinical challenge affecting up to a quarter of all breast cancer patients and is associated with a poorer clinical prognosis. This project focussed on exploring the role of Wnt signalling in endocrine resistant breast cancer cell models. Wnt pathway elements were deregulated in the acquired tamoxifen resistant cell line (Tam-R) compared to tamoxifen sensitive parental cells (MCF-7), with changes supportive of Wnt signalling activation in this tamoxifen resistant model apparent from Affymetrix HGU-133A gene microarray data and Western blot analysis. In contrast, Wnt signalling appeared to be suppressed based on Affymetrix data for MCF-7 cells treated with oestradiol for 10 days, with equivocal changes in MCF-7 cells treated with tamoxifen for 10 days or a faslodex resistant cell model (Fas-R). Excitingly, Tam-R cells were also more sensitive than MCF-7 cells to pharmacological manipulation of Wnt signalling. While Wnt activation using Wnt3a and LiCl did not affect cell growth or migration, inhibition of Wnt signalling usingIWP2, PNU 74654 and iCRT14 suppressed Tam-R cell growth and migration. There is mounting evidence of cross talk between Wnt and EGFR signalling in breast cancer, and EGFR activity is upregulated in Tam-R cells. The project’s findings tentatively supported cross-talk between the two signalling pathways in this model. Thus, targeting of the Wnt pathway alongside EGFR blockade was superior in suppressing cell growth and migration in Tam-R cells. The effect appeared to be more pronounced when Wnt signalling was inhibited at the nuclear level using iCRT14. Collectively, these data suggest that Wnt signalling may play an important role in tamoxifen resistance where it may offer an opportunity for more effective therapeutic intervention to control relapse and associated tumour aggressiveness.
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Cooper, Oliver Jamie. "Investigating Wnt signals in the avian somite." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445512.
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Lako, Majlinda. "Identifying and characterising novel human WNT genes." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242351.
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Nalesso, Giovanna. "WNT signalling in joint repair and homeostasis." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2347.
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Disruption of the Wnt canonical signalling leads to the development of osteoarthritis both in human and in mice but the underlying molecular mechanisms are poorly understood. Both forced activation and blockade of Wnt/β catenin signalling lead to cartilage breakdown. This study attempts to unravel the mechanisms leading to such paradox and is based on the hypothesis that WNT-3A triggers multiple signalling pathways simultaneously, with distinct outcomes. WNT-3A-stimulation induced activation of Wnt/β-catenin pathway in articular chondrocytes and promoted proliferation and loss of chondrocytes phenotype markers, such as COL2A1, Aggrecan and SOX9 mRNA. However, whereas the inhibition of the Wnt/β-catenin pathway by DKK1 rescued the proliferative effect of WNT-3A, it did not rescue the loss of chondrocyte phenotype but, paradoxically, it further enhanced it. Therefore I tested the possibility that WNT-3A-induced chondrocyte de-differentiation could be mediated by other WNT pathways independent of β-catenin. Indeed, in AHAC WNT-3A induced intracellular calcium mobilization and phosphorylation and nuclear localization of CaMKII in a G-protein dependent manner, suggesting the activation of the Wnt/CaMKII pathway. Inhibition of the Wnt/CaMKII pathway rescued the loss of the phenotypic markers SOX9 and COL2A1 induced by WNT-3A, indicating that this pathway drives WNT-3A-induced chondrocyte de-differentiation. Finally, my data show that the Wnt/β-catenin and the Wnt/CaMKII pathways are mutually inhibitory, explaining why both exogenous WNT-3A and its inhibitor DKK1 lead to chondrocyte de-differentiation: the first through direct activation of CaMKII, and the second indirectly by removal of the inhibition of CaMKII exerted by the β-catenin pathway. My results show for the first time that a single WNT ligand can simultaneously activate at least two different pathways in the same cells with different outcomes. These findings highlight the possibility to therapeutically target individual outcomes of Wnt signalling, for instance to prevent chondrocyte de-differentiation without affecting crucial anabolic processes such as cell proliferation.
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Leal, Letícia Ferro. "Via Wnt/?-catenina em tumores adrenocorticais pediátricos." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/17/17144/tde-06012016-181445/.
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Introdução: Em crianças das regiões Sul e Sudeste do Brasil há uma incidência elevada de tumores adrenocorticais (TAC). Anormalidades da ?-catenina tem sido encontradas em TAC em adultos e sugerem a ativação da via Wnt/ -catenina nestes tumores. No entanto, não há estudos avaliando o papel desta via em casuísticas de TAC pediátricos. Objetivos: Avaliar o papel da via Wnt/catenina e mutações do gene CTNNB1 na tumorigênese adrenocortical pediátrica. Indivíduos, Material e Métodos: Foram avaliados 62 pacientes pediátricos com TAC oriundos de dois centros de referência. Controles: córtex adrenal de indivíduos jovens com morte acidental. Avaliou-se a presença de mutação nos genes TP53 e CTNNB1. A expressão de genes da via Wnt (CTNNB1, o ligante WNT4, os inibidores SFRP1, DKK3 e AXIN1, o fator de transcrição TCF7 e os genes-alvo MYC e WISP2) foi avaliada por qPCR, utilizando-se o método de 2-Ct. Adicionalmente, a expressão de proteínas da via Wnt/-catenina e P53 foi avaliada por imunoistoquímica. Avaliou-se a relação entre possíveis anormalidades moleculares com o fenótipo clínico e o desfecho. Resultados: A sobrevida geral foi maior em pacientes menores que 5 anos de idade (p<0.0001) e em pacientes com estágios tumorais menos avançados (p<0.0001). A mutação P53 p.R337H foi encontrada em 87% dos pacientes e não se associou com características clinicopatológicas ou desfecho. Mutações do gene CTNNB1 foram encontradas em 4/62 (6%) TAC, todos carreadores da mutação P53 p.R337H. Houve associação entre óbito e presença de mutações do gene CTNNB1 (p=0,02). Acúmulo difuso da -catenina foi observado em 71% dos TAC, a maioria sem mutações do CTNNB1. Comparados a adrenais normais, os TAC apresentaram aumento da expressão do RNAm de CTNNB1 (p=0.008) e diminuição da expressão de genes inibidores da via Wnt: DKK3 (p<0.0001), SFRP1 (p=0.05) e AXIN1 (p=0.04). Com relação aos genes-alvo da via Wnt/-catenina, TAC apresentaram expressão aumentada de WISP2 e baixa expressão de MYC. Maior sobrevida geral foi associada à expressão baixa de SFRP1 (p=0.01), WNT4 (p=0.004) e TCF7 (p<0.01). Conclusões: Em TAC pediátricos, mutações somáticas ativadoras do gene CTNNB1 são pouco freqüentes e parecem estar associadas à maior ocorrência de óbito. Mesmo na ausência de mutações do gene CTNNB1, estes tumores apresentaram acúmulo de -catenina e do gene-alvo WISP2 e expressão reduzida de inibidores da via Wnt (DKK3, SFRP1 e AXIN1). Estes dados demonstram evidências de anormalidades na via Wnt/-catenina em TAC pediátricos, mesmo na ausência de mutações do gene CTNNB1. É provável que outros eventos genéticos afetando a via Wnt/-catenina estejam envolvidos na tumorigênese adrenocortical pediátricaContext: CTNNB1 mutations and activation of Wnt/-catenin pathway are frequent in adult adrenocortical tumors (ACTs) but data on childhood ACTs are lacking. Objective: To investigate Wnt/-catenin pathway abnormalities and CTNNB1 mutations in childhood ACTs. Patients and Methods: Clinicopathological findings and outcome of 62 childhood ACTs patients were analyzed regarding to CTNNB1/ -catenin mutations and to the expression of Wnt-related genes (CTNNB1, a Wnt ligand: WNT4, Wnt inhibitors: SFRP1, DKK3 and AXIN1, a transcription factor: TCF7, and target genes: MYC and WISP2) by qPCR and immunohistochemistry. Results: Overall survival (OS) was higher in patients younger than 5 years (p<0.0001) and associated with less advanced tumoral stage (p<0.0001). The p.R337H P53 mutation, found in 87% of the patients, was not associated with clinicopathological findings or outcome. CTNNB1 activating mutations were found in only 4/62 ACTs (6%), all of them harboring TP53 mutation. There was association between the presence of CTNNB1 mutation and death (p=0.02). Diffuse -catenin accumulation was found in 71% of ACTs, most of them without CTNNB1 mutation. CTNNB1 mutated ACTs presented weak/moderate -catenin accumulation. Compared to normal adrenals, ACTs presented increased expression of CTNNB1 (p=0.008) and underexpression of Wnt inhibitor genes: DKK3 (p<0.0001), SFRP1 (p=0.05) and AXIN1 (p=0.04). With regards to Wnt/-catenin target genes, ACTs presented lower expression of MYC but increased expression of WISP2. Higher overall survival was associated with underexpression of SFRP1 (p=0.01), WNT4 (p=0.004) and TCF7 (p<0.01). Conclusions: In childhood ACTs, CTNNB1 mutations are rare and appear to be associated with poor prognosis. Regardless of CTNNB1 mutations, these tumors presented reduced expression of Wnt inhibitor genes (DKK3, SFRP1 and AXIN1) and increased expression of CTNNB1 and a target gene, WISP2. Thus, besides CTNNB1 mutations, additional genetic events affecting the Wnt/-catenin pathway may be involved in childhood adrenocortical tumorigenesis.
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Giles, Adam Alexander. "Wnt signalling in oestrogen-induced lactotroph proliferation." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/wnt-signalling-in-oestrogeninduced-lactotroph-proliferation(35c1ba30-0755-4583-bdce-69dce1382721).html.
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The anterior pituitary gland is the major hormonal regulator in the body. The gland contains five secretory cell types whose emergence during development is defined by a tightly regulated array of transcription factors. In adult life, the gland is plastic with the relative proportions of cells varying depending on physiological context. Tumours of the pituitary gland account for 15% of all intracranial tumours in man and are caused by the selective proliferation of one of the secretory cell types. The majority of these (60%) are prolactinomas which consist of very slowly proliferating lactotroph cells, which produce the hormone prolactin. Pituitary tumours are almost never malignant and do not express common genetic markers for cancer, suggesting endogenous proliferative stimuli in the pituitary are the cause of tumour development. Oestrogen causes lactotroph hyperplasia during pregnancy and increases prolactin secretion. Our group previously showed that Wnt-4 mRNA was upregulated during oestrogen-induced lactotroph hyperplasia in Fischer 344 rats. Wnt molecules are key regulatory proteins controlling differentiation, proliferation and migration in development and adult life. Wnt-4 is involved in the emergence of lactotrophs during development, and has been implicated in pituitary tumour formation. Wnt molecules signal through three pathways. The well studied canonical pathway has been implicated in numerous cancers and centres around gene transcription initiated by translocation of β-Catenin into the nucleus. There are two non-canonical pathways: the Wnt-planar cell polarity (PCP) pathway and the Wnt-calcium pathway which are both poorly understood. In this thesis, the expression of Wnt-4 was studied in the pituitary, and effects of downstream signalling pathways in response to oestrogen were assessed. Wnt-4 was expressed in all secretory cell types of the pituitary, as well as the marginal zone (MZ), a region of the pituitary that may harbour stem cells. Oestrogen upregulated Wnt-4 protein in the somatolactotroph GH3 cell line, though this could not be replicated in primary tissue. A number of approaches (western blotting, immunofluorescence, reporter gene assays and mutant β-Catenin overexpression) were utilised to show that the canonical pathway was not activated in the pituitary. Wnt-4 had a clear inhibitory effect on calcium oscillations in GH3 cells, showing for the first time a non-canonical effect in the pituitary, though the downstream effects are currently unknown. Attempts made to study the activation of the PCP pathway were inconclusive. Efforts focused on the distribution of key structural and regulatory proteins in the anterior pituitary and the MZ. The MZ was characterised by a single layer of cells at the border of the anterior and intermediate lobes of the pituitary, with high expression of E-Cadherin and Sox 9, though no change in distribution was observed with oestrogen treatment. In the anterior lobe, oestrogen treatment decreased N and E-Cadherin expression, which could be an indicator of PCP pathway activation during oestrogen induced-lactotroph hyperplasia. Overall, data suggest that Wnt-4 does not directly cause oestrogen-induced lactotroph proliferation, but is likely to play a role in regulating tissue plasticity in the adult gland, as well as in the pathogenesis of pituitary tumours.
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Heiser, Patrick W. "Wnt signaling in pancreas development and disease." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3261237.
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Arnold, Sebastian Johannes. "Wnt-, beta- Catenin Zielgene der frühen Mausentwicklung." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10047791.
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Wehrle, Christian. "Wnt/beta-Catenin-Zielgene in der Mausentwicklung." [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11126466.
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Sheldahl, Laird Charles. "Molecular components of the Wnt/calcium pathway /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/6294.
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Louie, Sarah. "Wnt signaling regulated by Frizzled and HIPK1 /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6267.
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Annavarapu, Srinivas Rao. "Characterisation of Wnt signalling pathway in rhabdomyosarcoma." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3009225/.
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Introduction: Rhabdomyosarcoma (RMS) remains one of the most challenging tumours in paediatric oncology, accounting for around 5% of all malignant paediatric tumours. Of the two major subtypes of RMS, embryonal and alveolar, the latter portends a poorer clinical outcome. Canonical Wnt signalling pathway is an important evolutionarily conserved signalling pathway that is required for muscle development and embryonal somite patterning. β-Catenin is a potent nuclear transcriptional activator and is the central effector of the canonical Wnt signalling pathway. Interestingly, constitutional activation of Wnt signalling also promotes tissue invasion and metastasis in various tumours. Aims: This study aims to characterise the canonical Wnt/β-catenin signalling in paediatric RMS to assess its functional relevance to the tumourigenesis of RMS and to investigate if modulation of this pathway could provide a therapeutic target for RMS. Results: When we evaluated the immunohistochemical expression of β-catenin in the paraffin-embedded tissues derived from 44 RMS patients, we found positive expression in 26 cases. There was positive expression of β-catenin in the cytoplasm or the cell membrane of alveolar (9/14) and embryonal RMS (15/30); nuclear staining was only seen in two embryonal RMS cases. Next, we assessed β-catenin expression by immunoblot analysis in four RMS cell lines - RD and RD18 (embryonal); Rh4 and Rh30 (alveolar). We were able to demonstrate expression of major canonical Wnt proteins in all cell lines that included: β-catenin, glycogen synthase kinase-3β, disheveled, axin-1, naked and LRP-6. To assess the functional significance of these proteins, we incubated the RMS cell lines with human recombinant Wnt3a to stimulate the Wnt signalling pathway. Thereafter, by using cellular fractionation and immunofluorescence experiments, we demonstrated change in the phosphorylation status of β-catenin, stabilisation of its active form and its nuclear translocation. By employing a TOP/FOP flash reporter gene assay, we showed a T-cell factor/lymphoid-enhancing factor (TCF/LEF)-mediated transactivation. In addition, we found a significant decrease in the proliferation rate of the alveolar RMS cells after Wnt3a stimulation. This decrease in proliferation rate was thought to be due to the concomitant activation of myodifferentiation as seen by the immunoblot expression of myogenin, MyoD1 and myf5. Our data indicates that the major regulatory proteins of the canonical Wnt/β-catenin signalling are expressed in RMS and that functional activation of this pathway, at least in a subset of RMS, may represent a novel therapeutic target.
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Derry, Sarah White. "Calcium induced Naked1 activity in Wnt signaling." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/6565.
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The Wnt signaling network has critical roles in development and disease. Simplified, this complex network has two distinct outputs: the Wnt/β-catenin module activates the phosphoprotein Dishevelled (Dvl) and leads to transcriptional activation while the Wnt/Planar Cell Polarity (PCP) module activates Dvl and leads to calcium release and directed cell movement. Wnt/β-catenin and Wnt/PCP share signaling components like Frizzled receptors, Dvl, and Naked (Nkd). It is an open question how converging Wnt signals diverge into separate outcomes. In this thesis, I used molecular techniques, functional studies in the zebrafish, and biochemical approaches to determine the role of Nkd in Wnt signaling.
Nkd contains and EF-hand, a putative calcium binding domain, and is known to antagonize Wnt/β-catenin and disrupt Wnt/PCP signaling. We utilized a tissue that requires both Wnt/β-catenin and Wnt/PCP signaling to properly pattern the left/right axes of the embryo; the dorsal forerunner cells (DFCs). The DFCs exhibit aperiodic calcium release as they migrate to form the Kupffer's Vesicle (KV), the organ of asymmetry. Calcium inhibition in the DFCs disrupts their migration, alters KV formation, and disrupts left/right patterning. Nkd is enriched in the DFCs during migration and KV formation and endogenous Nkd knockdown in the DFCs produces the same phenotypes as calcium inhibition, making Nkd a candidate molecule for directing converging Wnt signals to distinct outcomes.
To assess the role of the EF-hand in Nkd function, I created point mutations predicted to disrupt EF-hand affinity for calcium. Through functional studies in zebrafish embryos, I determined that Nkd EF-hand is necessary for Nkd function in Wnt/PCP signaling, but dispensable for Wnt/β-catenin signaling. Although Nkd has not been shown to bind calcium, our functional data with the Nkd EF-hand point mutant provides compelling evidence for a role for calcium in Nkd function in directing Wnt signaling output.
EF-hand affinity for calcium is influenced by binding partners, and since Nkd binds to Dvl in the Dvl PDZ domain, we screened the domain for a region rich in amino acids that facilitate ion binding. We identified a 12-amino acid sequence in the Dvl PDZ domain with potential to create a negatively charged pocket to help coordinate calcium binding. We expressed the Nkd EF-hand (EFX) Dvl basic domain and PDZ domain (bPDZ). The purified EFX and bPDZ constructs were used to investigate the interaction between Nkd, Dvl, and calcium. I show, by circular dichroism, that the Nkd/Dvl complex undergoes a calcium-induced change in secondary structure. This reveals the mechanism by which Nkd directs Dvl from the default Wnt/β-catenin signaling module to the Wnt/PCP module in response to calcium.
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Ziegler, Slava. "Identifizierung und Charakterisierung neuer tumorrelevanter Gene, die unter Kontrolle des Wnt-[beta]-Catenin-Signalwegs [Wnt-beta-Catenin-Singalwegs] stehen." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971635307.
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Kramer, Monika [Verfasser]. "The WNT/β-catenin [WNT-beta-catenin] pathway : profibrotic signaling in fibroblasts in idiopathic pulmonary fibrosis / vorgelegt von Monika Kramer." Giessen : VVB Laufersweiler, 2010. http://d-nb.info/1009523570/34.
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Vouyovitch, Cécile. "Implication de l’hormone de croissance autocrine dans le cancer du sein humain." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10131.
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Notre équipe a entrepris des travaux qui ont permis d’établir un lien causal entre la production autocrine de hGH et la stimulation des propriétés prolifératives, anti-apoptotiques, migratoires et invasives des cellules carcinomateuses mammaires humaines. Ces travaux permettent aujourd’hui de considérer l’action de la hGH autocrine comme celle d’un véritable oncogène. Mon travail de thèse s’est intéressé à comprendre les effets de la hGH autocrine dans la progression tumorale mammaire selon deux axes de recherche. Le premier étant de définir le rôle de la GH autocrine dans l’angiogenèse tumorale et le second de déterminer les interactions entre la voie de signalisation de la GH autocrine et la voie de signalisation Wnt. Nous avons démontré dans notre première étude que la production autocrine de hGH par les cellules carcinomateuses mammaires MCF7 favorise la prolifération, la survie, la migration et l’invasion des cellules micro-vasculaires endothéliales HMEC1, ainsi que leurs capacités à former des tubes in vitro. Ces effets cellulaires observés sont médiés par le GHR à exprimé sur les cellules endothéliales et sont la conséquence d’une augmentation d’expression du facteur pro-angiogénique VEGF-A. L’utilisation de l’antagoniste du VEGF-A, le bevacizumab, inhibe les effets vasculaires induits par la hGH autocrine. Ces effets retrouvés in vivo soulignent la pertinence de la production de GH autocrine par les cellules cancéreuses mammaires. Grâce à un modèle de xénogreffe de cellules carcinomateuses mammaires humaines nous avons montré que le développement soutenu de l’angiogenèse et de la lymphogenèse tumorales sont activés par la GH autocrine. La production de hGH autocrine par les cellules cancéreuses mammaires est donc un acteur de l’expansion du réseau vasculaire des cancers du sein. La voie de signalisation Wingless (Wnt) est un déterminant critique du contrôle cellulaire durant le développement mais également chez l’adulte. Nous avons démontré que la hGH autocrine stimule l’expression de différents acteurs de la voie Wnt et notamment la protéine sécrétée WNT4. Une surexpression de WNT4 est identifiée sur des biopsies de cancer du sein par rapport au sein normal. La production de WNT4 exerce un effet synergique avec la GH autocrine sur la stimulation de la prolifération des cellules carcinomateuses mammaires par un mécanisme dépendant de JAK2. Surexprimé dans des cellules épithéliales mammaires humaines, WNT4 stimule leurs propriétés prolifératives, anti-apoptotiques et migratoires et induit la formation de colonies en agar. Ces effets sont médiés par l’activation transcriptionnelle et traductionnelle de protéines clés du cycle et de la survie cellulaires. Des changements phénotypiques sont induits par la surexpression de WNT4 dans les cellules épithéliales mammaires et associés à l’augmentation d’expression de marqueurs mésenchymateux, d’acteurs du remodelage du cytosquelette et d’activateurs de la migration cellulaire. La progression tumorale mammaire humaine est donc induite par les effets autocrines de la hGH sur la production de WNT4 et la surexpression épithéliale mammaire de WNT4 permet l’établissement d’un phénotype pré-oncogéniqueStudies of our group demonstrated that autocrine human growth hormone promotes proliferation, apoptotic resistance, invasion and migration of human mammary carcinoma cells. The objective of my Ph.D was to understand the role of autocrine hGH in mammary tumour progression following two aspects. On one hand, characterising its impact on tumour angiogenesis and then analysing the crosstalk between GH and Wnt signalling pathways. In the first part, we demonstrated that autocrine hGH from human mammary carcinoma cell line MCF- 7, stimulates proliferation, survival, migration and invasion of human microvascular endothelial cell line and enhances in vitro tubulogenesis. These effects are mediated through the hGHR and stimulates the expression of the proangiogenic factor VEGF-A. Antagonizing VEGF-A action with bevacizumab inhibited the proangiogenic actions of autocrine hGH in vitro. Using a xenograft nude mice model we have shown that sustained angiogenesis and lymphangiogenesis are activated by autocrine hGH production by mammary carcinoma cells. Thus, autocrine hGH participates in the expansion of the vascular network during breast cancer formation. The Wingless (Wnt) signalling pathway is an important actor during embryonic development and in the adult. Here, we showed that autocrine hGH stimulates the expression of several actors of the Wnt pathway, including WNT4. Human breast cancer biopsies overexpressed WNT4 as compared to normal breast. WNT4 production is JAK2 kinase-dependent and synergizes with autocrine hGH on mammary carcinoma cell proliferation. Forced expression of WNT4 in normal human mammary epithelial cell lines stimulates their proliferative, survival and migratory capacities and the formation of colonies in soft agar. These effects are mediated through the transcriptional and translational activation of key regulators of cell cycle and survival. Phenotypic changes are induced by forced expression of WNT4 in mammary epithelial cells and associated with increased expression of mesenchymal markers, cytoskeletal remodelling factors and cell migration activators. Human breast cancer progression is thus activated by autocrine effects of hGH on WNT4 expression and deregulated expression of WNT4 in mammary epithelial cells induces the establishment of a pre-tumorigenic phenotype
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Martin, Jennifer. "Wnt regulated transcription factor networks mediate vertebrate cardiogenesis." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Online version available for University members only until Feb. 15, 2012, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25801.
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Papoutsi, Tania. "Regulation of cardiogenesis by putative WNT signalling pathways." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1325.
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The Wnt/ -catenin and the Wnt/planar cell polarity (Wnt/PCP) signalling pathways have been shown to play important roles in cardiogenesis and their disruption has been shown to cause severe disturbances in heart development. Spatially and temporally complex interplays between the two pathways have been described. One component of the PCP pathway is Jnk, a member of the highly conserved mitogenactivated protein kinase (MAPK) family. This stress responsive mitogen is known to control a variety of cellular behaviours such as proliferation, apoptosis and cell migratory behaviour and as such, is likely to be of pivotal importance in cardiac development. The aim of this study was to investigate the role played by Jnk in vertebrate heart formation and the relationships between Jnk signalling and canonical Wnt signalling, using in silico and in vivo approaches in zebrafish and an in vitro approach on a mouse embryonic stem (ES) cell model of cardiogenesis. Firstly, using a range of bioinformatic methods, an analysis of jnk genes, splice variants and proteins, and an investigation of their phylogenetic relation with other species was undertaken. This suggested conservation of Jnk family members, but suggested that there were additional orthologues of jnk1 present in the zebrafish transcriptome. The spatial and temporal expression profiles of these genes were then examined by semi-quantitative PCR and in situ hybridisation. The functional role of Jnk proteins during zebrafish development was subsequently investigated using a specific chemical inhibitor, SP600125. Inhibition of Jnk signalling during gastrulation and somitogenesis caused a convergence extension-like phenotype and severe cardiac defects, including looping anomalies and alterations in atrial versus ventricular cell numbers. ES cells have the capacity to differentiate in vitro and give rise to cells of many different lineages, including cardiomyocytes. Canonical Wnt and Jnk components were manipulated during specific windows of differentiation as ES cells formed beating embryoid bodies. Examination of the spontaneous contractile behaviour of differentiating ES cells as they entered the cardiogenic lineage, and analysis of their developmental gene expression profiles, showed the beating behaviour of ES cellderived cardiac cells was enhanced in a temporally specific manner after inhibition of the non-canonical Wnt/Jnk pathway, while there was marked alteration of canonical Wnt signalling. To investigate whether there were reciprocal interactions between the two pathways, analysis of the system after activation of the canonical pathway was also undertaken. These studies indicated that the beating behaviour of ES cell-derived cardiac cells was enhanced in a temporally specific manner after inhibition of Jnk, while after activation of canonical Wnt/ -catenin signalling, the cardiogenic potential of differentiating ES cells was severely suppressed. The findings of this study extend our understanding of the role played by canonical and non-canonical Wnt signalling pathways in heart morphogenesis and highlight the interacting effects of related signalling pathways activity in cardiogenesis.
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Simeonidis, Iordanis. "The role of WNT signalling in central synaptogenesis." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497269.
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Lucas, Fiona Ralitsa. "The role of WNT-7a in cerebellar development." Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394389.
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Antoni, Laurent Paul. "The regulation of myogenic differentiation by WNT signalling." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414996.
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