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Identification and characterization of novel regulators of hematopoietic stem cell function
Grušanović, Srđan ; Alberich Jorda, Meritxell (advisor) ; Balounová, Jana (referee) ; Froňková, Eva (referee)
Hematopoietic stem cells (HSCs) are sitting atop a carefully orchestrated system, called the hematopoietic system. HSCs maintain the constant production of mature blood cells throughout our life, and dysregulated HSC function may lead to severe health problems including bone marrow aplasia and leukemia. Thus, HSC activity needs to be tightly controlled by a complex network of cell intrinsic and cell extrinsic factors. In this thesis, we focus on two previously uncharacterized extrinsic mechanisms that might be involved in the regulation of HSC function. A common aspect of these mechanisms is the production of pro-inflammatory cytokines. First, we investigated the impact of donor NK cells on donor HSC function upon bone marrow transplantation, a frequent clinical intervention. We observed that NK cells negatively affect HSC engraftment and reconstitution during transplantation. To address the potential mechanism, we employed Cebpg knockout mice, which produce non-functional NK cells, and determined that NK cells affect HSC activity through the production of IFNγ. Remarkably, IFNγ-blocking antibodies improved murine and human HSC activity upon bone marrow transplantation. Altogether, we concluded that suppression of inflammatory signals generated by donor innate immune cells can have a significant...
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Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii
Žídek, Radim ; Kozmik, Zbyněk (advisor) ; Janečková, Lucie (referee) ; Macůrková, Marie (referee)
Radim Žídek "Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii" (dissertation) Abstract: Wnt/β-catenin signalling is absolutely crucial for the early embryonic development of metazoan animals from the establishment of body axes, through the specification of germ layers and tissues to the development of organ systems. I used pharmacological manipulations of the Wnt/β-catenin pathway activity in the planktonic larvae of the marine polychaete annelid Platynereis dumerilii, the representative of the clade Spiralia, to investigate the role of Wnt/β- catenin signalling in the development and evolution of three hallmarks of Bilateria: the central nervous system, the body segmentation and the digestive tube. Wnt proteins are produced in all three aforementioned systems in Platynereis where they trigger the Wnt/β-catenin pathway in neighbouring cells. I describe here, for the first time in Platynereis, a homologue of the endpoint transcription factor of the entire pathway, Pdu-Tcf, which is subjected to an alternative splicing and along with a Wnt target gene Pdu-Axin is expressed in tissues with the active Wnt signalling - in the brain ganglia, in the neuroectoderm along the ventral midline, in segments, in the posterior growth zone and in the gut. Pharmacological manipulations...
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Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii
Žídek, Radim
Radim Žídek "Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii" (dissertation) Abstract: Wnt/β-catenin signalling is absolutely crucial for the early embryonic development of metazoan animals from the establishment of body axes, through the specification of germ layers and tissues to the development of organ systems. I used pharmacological manipulations of the Wnt/β-catenin pathway activity in the planktonic larvae of the marine polychaete annelid Platynereis dumerilii, the representative of the clade Spiralia, to investigate the role of Wnt/β- catenin signalling in the development and evolution of three hallmarks of Bilateria: the central nervous system, the body segmentation and the digestive tube. Wnt proteins are produced in all three aforementioned systems in Platynereis where they trigger the Wnt/β-catenin pathway in neighbouring cells. I describe here, for the first time in Platynereis, a homologue of the endpoint transcription factor of the entire pathway, Pdu-Tcf, which is subjected to an alternative splicing and along with a Wnt target gene Pdu-Axin is expressed in tissues with the active Wnt signalling - in the brain ganglia, in the neuroectoderm along the ventral midline, in segments, in the posterior growth zone and in the gut. Pharmacological manipulations...
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Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii
Žídek, Radim
Radim Žídek "Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii" (dissertation) Abstract: Wnt/β-catenin signalling is absolutely crucial for the early embryonic development of metazoan animals from the establishment of body axes, through the specification of germ layers and tissues to the development of organ systems. I used pharmacological manipulations of the Wnt/β-catenin pathway activity in the planktonic larvae of the marine polychaete annelid Platynereis dumerilii, the representative of the clade Spiralia, to investigate the role of Wnt/β- catenin signalling in the development and evolution of three hallmarks of Bilateria: the central nervous system, the body segmentation and the digestive tube. Wnt proteins are produced in all three aforementioned systems in Platynereis where they trigger the Wnt/β-catenin pathway in neighbouring cells. I describe here, for the first time in Platynereis, a homologue of the endpoint transcription factor of the entire pathway, Pdu-Tcf, which is subjected to an alternative splicing and along with a Wnt target gene Pdu-Axin is expressed in tissues with the active Wnt signalling - in the brain ganglia, in the neuroectoderm along the ventral midline, in segments, in the posterior growth zone and in the gut. Pharmacological manipulations...
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Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii
Žídek, Radim ; Kozmik, Zbyněk (advisor) ; Janečková, Lucie (referee) ; Macůrková, Marie (referee)
Radim Žídek "Wnt/β-catenin signalling in the development of the marine annelid Platynereis dumerilii" (dissertation) Abstract: Wnt/β-catenin signalling is absolutely crucial for the early embryonic development of metazoan animals from the establishment of body axes, through the specification of germ layers and tissues to the development of organ systems. I used pharmacological manipulations of the Wnt/β-catenin pathway activity in the planktonic larvae of the marine polychaete annelid Platynereis dumerilii, the representative of the clade Spiralia, to investigate the role of Wnt/β- catenin signalling in the development and evolution of three hallmarks of Bilateria: the central nervous system, the body segmentation and the digestive tube. Wnt proteins are produced in all three aforementioned systems in Platynereis where they trigger the Wnt/β-catenin pathway in neighbouring cells. I describe here, for the first time in Platynereis, a homologue of the endpoint transcription factor of the entire pathway, Pdu-Tcf, which is subjected to an alternative splicing and along with a Wnt target gene Pdu-Axin is expressed in tissues with the active Wnt signalling - in the brain ganglia, in the neuroectoderm along the ventral midline, in segments, in the posterior growth zone and in the gut. Pharmacological manipulations...
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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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Molecular mechanisms of Wnt signalling in mammalian cells
Lukáš, Jan ; Kořínek, Vladimír (advisor) ; Kohoutová, Milada (referee) ; Macůrková, Marie (referee)
Wnt signalling represents an important mechanism participating in control of cellular and developmental processes, including establishment of cell polarity, cell fate specification, stem cell self-renewal, tissue patterning and organogenesis, homeostasis maintenance and regeneration. Misregulation of the Wnt signalling during embryogenesis leads to developmental defects while aberrant activation later in development is associated with degenerative diseases and a number of cancers. The presented PhD thesis is based on four original publications that deal with the post-translational modifications of Wnt ligands and molecular mechanisms contributing to the regulation of a transcriptional profile of the so-called canonical Wnt pathway. Wnt signalling pathway is used repetitively both in time and different cellular contexts throughout development of multicellular organisms. Inevitably, in each single situation -catenin/TCF complexes, the downstream effectors, induce only subsets of all potential target genes. How this differential tissue- and stage-specific control over various subsets of target genes is achieved with such a limited number of nuclear effectors is not fully understood. Along with the expression of specific LEF/TCF family members or their variants containing different functional domains...
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Wnt signaling inside out
Doubravská, Lenka ; Kořínek, Vladimír (advisor) ; Stopka, Tomáš (referee) ; Krylov, Vladimír (referee)
Signaling pathways function as molecular instruments mediating cellular response to intrinsic and extrinsic inputs, which can consequently lead to cell division or differentiation on one side and cell death on the other. Molecular network of different pathways enables the intercellular communication and hence the whole organism can exist and function coordinately. The Wnt signaling pathway belongs among evolutionarily old and conserved molecular pathways and acts in many different processes during development. Moreover, it is necessary for maintenance of adult tissues as it participates in regeneration. Diverse malignancies, where repressive components of the Wnt pathway are non-functional, represent seamy side of the scope. This thesis is based on 4 publications covering Wnt signaling on very multifarious levels. Firstly, I focus on processing of Wnt protein which stands at the beginning of the cascade as extracellular morphogen. Secondly, survival effect of Wnt producing fibroblasts on leukemia cells after induction of apoptosis by ligand TRAIL is discussed. The third issue shows novel components of the Wnt signaling pathway and introduces us into nucleus - "bottom" level of the pathway. 1. Fatty acid modification of Wnt1 and Wnt3a at serine is prerequisite for lipidation at cysteine and is...
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