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Wingless/Notch crosstalk in Drosophila melanogaster
Hajšmanová, Hana ; Mašek, Jan (advisor) ; Macůrková, Marie (referee)
Fundamental for the existence of multicellular organisms is the presence signalling pathways, complex biochemical cascades, allowing reciprocal communication amongst the cells. Both Notch and Wnt pathways are crucial for embryonic development and their deregulation leads to many severe diseases. Decades of research, largely based on model organism D. melanogaster, showed that components of these pathways do not function strictly separately but on contrary interact with each other (crosstalk). This phenomenon is explored only to a lesser extent in mammals. The aim of this thesis is to recapitulate existing findings of Wnt/ Notch crosstalk in D. melanogaster and outline where crosstalk could play a role in mammals.
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Induction of neurogenesis and gliogenesis after ischemic CNS injury - the role of Wnt signaling pathway
Koleničová, Denisa ; Anděrová, Miroslava (advisor) ; Nerandžič, Vladimír (referee)
This bachelor thesis is focused on ischemic injury of the central nervous system (CNS), one of the most frequent causes of death and disability in the world, and its possible treatment via the induction of neurogenesis. It consists of three different parts. In the first part, main neurogenic regions of the CNS, the subventricular zone and gyrus dentatus (GD) of the hippocampus, are described at the cellular, as well as molecular level. The second part is mainly dedicated to ischemic injury, to the global and focal brain ischemia. A particular chapter of this part describes changes in neurogenesis and gliogenesis after ischemic injury of the brain, changes in the induction of radial glial cells, proliferation and migration of neural progenitor cells and neuroblasts. In this chapter, we also describe the activation of astrocytes, microglia and NG2 glia (also known as polydendrocytes) after ischemic injury of the CNS. The last, third part of the bachelor thesis, is focused on signaling pathways, which significantly influence neurogenesis: Shh (Sonic hedgehog homolog), Notch and Wnt (Wingles/Integrated) signaling pathways. Special attention is devoted to the Wnt signaling pathway, which is an essential part of molecular mechanisms in nerve cells. Keywords: neurogenesis, gliogenesis, hippocampus, gyrus...
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Characterization of mice with constitutively active Wnt/beta-catenin signaling pathway in lens
Antošová, Barbora ; Kozmik, Zbyněk (advisor) ; Pavlínková, Gabriela (referee)
Lens development and differentiation are strictly regulated processes. Various disturbances of these processes can lead to vision-limiting pathologies. The vertebrate lens is composed of epithelial cells and terminally differentiated fiber cells. Differentiation of fiber cells is connected with expression of fiber cell specific proteins (such as crystallins), cell cycle exit, and finally with the degradation of cell nucleus and organelles. Wnt/β-catenin signaling plays important roles during early eye development as well as later during the lens differentiation. To investigate the consequences of constitutive activation of Wnt/β-catenin signaling in lens fiber cells transgenic mouse strain, called CLEF, was created. Constitutive activation of Wnt/β-catenin signaling in fiber cells of CLEF mouse is achieved by transgenic protein CLEF that contains C-terminal activation domain of β-catenin fused to the amino terminus of full-length protein Lef1. The expression of CLEF transgene is under the control of αA-crystallin promoter. As a result of constitutive activation of Wnt/β-catenin signaling in fiber cells, adult CLEF mice develop cataracts and microphthalmia, and the morphology of adult mutant lenses is disrupted. Transgenic CLEF mRNA is expressed starting from E13.5 and by E16.5 transgenic CLEF protein is...
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The role of phosphatidylinositol-4-phosphate 5-kinase PPK-1 in Wnt signalling regulation in Caenorhabditis elegans
Zavadilová, Kristýna ; Macůrková, Marie (advisor) ; Kostrouch, Zdeněk (referee)
The Wnt signalling pathway is highly conserved signalling among Eukaryotes that regulates many cellular processes. In particular, it plays a role during invidual's development, but it is also important at later stage of life, when it is involved in maintaining homeostasis in the body. Recent studies have shown that phosphatidylinositol-4-phospahte 5-kinase (PIP5K), which is key to the production of phosphatidylinositol (4,5)-bisphosphate in the cell, is also involved in regulation of the canonical Wnt signalling cascade. In mammalian cells, a model has been described in which PIP5K is involved in signal transduction in a Wnt receiving cell. We decided to verify the involvement of PIP5K in the regulation of Wnt signalling also in Caenorhabditis elegans, an excellent model organism for study of signalling pathways, and thus contribute to a better understanding of this evolutionarily conserved pathway. In this work, we found that decreased expression of PPK-1/PIP5K in wild type animals does not result in Wnt signalling disruption. Nevertheless, in conditions, where the activity of Wnt signalling is already reduced, decrease in PPK-1 levels leads to defective migration of the QL neuroblast daughter cell. By analyzing the migration of QL progeny, which is controlled by EGL-20/Wnt dependent Wnt...
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The role of the Wnt signalling pathway in proliferation and differentiation of neural stem cells in the neonatal and adult mouse brain
Koleničová, Denisa ; Anděrová, Miroslava (advisor) ; Janečková, Lucie (referee)
The canonical Wnt/β-catenin signalling pathway plays an important role in proliferation and differentiation of neural progenitors during embryogenesis as well as postnatally. In the present study, the effect of the Wnt signalling pathway on the differentiation potential of neonatal and adult neural stem cells (NS/PCs) isolated from subventricular zone (SVZ) of lateral ventricles and their membrane properties were studied eight days after the onset of in vitro differentiation. To manipulate Wnt signalling at different cellular levels, three transgenic mouse strains were used, which enabled inhibition or activation of the pathway using the Cre- loxP system. We showed that the activation of the Wnt signalling pathway leads to higher expression of β-catenin in both postnatal as well as adult NS/PCs, while Wnt signalling inhibition results in the opposite effect. To follow the fate of NS/PCs, the patch-clamp technique, immunocytochemistry, and Western blot were employed. After eight days of NS/PCs differentiation we identified three electrophysiologically and immunocytochemically distinct cell types of which incidence was significantly affected by the canonical Wnt signalling pathway, only in differentiated neonatal NS/PCs. Activation of this pathway suppressed gliogenesis, and promoted neurogenesis,...
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The role of transcriptional factor Tcf7l1 and Wnt/β-catenin signaling pathway during differentiation of the head ectoderm.
Mašek, Jan ; Kozmik, Zbyněk (advisor) ; Černý, Robert (referee) ; Procházka, Jan (referee)
Differentiation of the head ectoderm is crucial for the evolutionary diversification of vertebrates. Expression of the genes responsible for this process is orchestrated troughout complex gene regulatory networks that are induced and modulated by Wnt, FGF and BMP signaling pathways. In addition, Wnt/β-catenin signaling, in combination with expression of the Wnt antagonists from the rostral-most part of the head ectoderm, represent a key source of information for the regionalization of the tissue along the antero-posterior axis. This allows the differentiation of the anterior ectoderm that gives rise to the anterior neural fold (ANF) and anterior part of the presumptive placodal region (PPR), and more posterior ectoderm where higher levels of active Wnt/β-catenin signaling promote differentiation into the neural crest (NC) and posterior PPR. Although the requirement of Wnt/β-catenin signalling for ANF, PPR and NC development has been intensively studied in non-mammalian vertebrate model organisms, we lack a clear picture about the situation in mammals. Furthermore, current knowledge in mammals has been gathered via experiments on the level of β-catenin and very little is known about the individual roles of the Tcf/Lef transcription factors. Thereby, we decided to manipulate the Tcf7l1, member of the...
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Induction of neurogenesis and gliogenesis after ischemic CNS injury - the role of Wnt signaling pathway
Koleničová, Denisa ; Anděrová, Miroslava (advisor) ; Nerandžič, Vladimír (referee)
This bachelor thesis is focused on ischemic injury of the central nervous system (CNS), one of the most frequent causes of death and disability in the world, and its possible treatment via the induction of neurogenesis. It consists of three different parts. In the first part, main neurogenic regions of the CNS, the subventricular zone and gyrus dentatus (GD) of the hippocampus, are described at the cellular, as well as molecular level. The second part is mainly dedicated to ischemic injury, to the global and focal brain ischemia. A particular chapter of this part describes changes in neurogenesis and gliogenesis after ischemic injury of the brain, changes in the induction of radial glial cells, proliferation and migration of neural progenitor cells and neuroblasts. In this chapter, we also describe the activation of astrocytes, microglia and NG2 glia (also known as polydendrocytes) after ischemic injury of the CNS. The last, third part of the bachelor thesis, is focused on signaling pathways, which significantly influence neurogenesis: Shh (Sonic hedgehog homolog), Notch and Wnt (Wingles/Integrated) signaling pathways. Special attention is devoted to the Wnt signaling pathway, which is an essential part of molecular mechanisms in nerve cells. Keywords: neurogenesis, gliogenesis, hippocampus, gyrus...
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Mechanismy regulace aktivity proteinu MTM-6 na endosomech.
Horázná, Monika ; Macůrková, Marie (advisor) ; Fafílek, Bohumil (referee)
Wnt signalling belongs to conserved pathways and mediates cell fate decision, development, regeneration and adult tissue homeostasis. Disruption or misregulation of Wnt signalling pathway often leads to disease. Wnt proteins are hydrophobic glycoproteins which need a special receptor for transport from Golgi Apparatus to cell surface, which is called MIG-14 in Caenorhabditis elegans and Wntless (Wls) in mammals. In this study, I focus on understanding mechanisms that regulate MTM-6 protein activity. MTM-6, a lipid phosphatase associated with endosomal membrane, has been recently identified as a regulator of MIG-14/Wls trafficking in Caenorhabditis elegans. Silencing of mtm-6 leads to misregulation of some Wnt-directed processes, such as migration of Q neuroblasts progeny. This study reports identification of novel mtm-6 genetic interactors that have been found to influence migration of Q neuroblasts progeny through Wnt signalling. New knowledge about mtm-6 genetic interactions bring us near to understanding of Wnt signalling regulation. Keywords: Caenorhabditis elegans, MTM-6, SEL-5, Wntless, Wnt, endosomes, phosphoinositides, retromer
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The role of endocytosis in Wnt signaling pathway
Matějů, Daniel ; Libusová, Lenka (advisor) ; Doubravská, Lenka (referee)
Endocytosis and cell signaling are tightly connected processes. This connection is most obvious at the level of endocytosis of signaling receptors and ligands. For many years, endocytosis of signaling receptors was considered as a negative feedback loop mechanism, which desensitizes the cell after prolonged stimulation by ligand. Now it is evident that the situation is more complex and endocytosis can affect cell signaling both negatively and positively. In this thesis, I will summarize how Wnt signaling can be affected by endocytosis of receptors and ligands of this signaling pathway. Wnt signaling is one of the most important and intensively studied signaling pathways in the metazoan development. Several possible roles of endocytosis in Wnt signaling were uncovered in recent years, some of them unique among other signaling pathways. Understanding the relationship between endocytosis and Wnt signaling will thus help not only to deepen the knowledge of Wnt signaling but also to shed light on the possible roles of endocytosis in regulation of cell signaling in general.
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