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Mechanizmy regulace signální transdukce povrchovými proteiny leukocytu*.
Štěpánek, Ondřej ; Brdička, Tomáš (advisor) ; Brábek, Jan (referee) ; Vomastek, Tomáš (referee)
The core of the doctoral thesis "Regulation of signal transduction by leukocyte surface proteins" consists of three publications in international peer-reviewed journals dealing with leukocyte signaling both at the level of individual signaling pathways and in the context of a multicellular organism. Most attention is paid to signaling via the T cell receptor (TCR), which plays a central role in the development and function of T cells and represents a key signaling pathway for proper function of the adaptive component of the immune system. Transmembrane protein tyrosine phosphatase CD148 was considered a negative regulator of TCR signaling through dephosphorylation of LAT and PLCγ1 proteins. This study brings evidence that CD148 is able to modulate signaling also at the level of Lck, both positively and negatively. The net effect of CD148 activity on the TCR signaling is determined by the intracellular biochemical context, notably, the presence of another tyrosine phosphatase CD45. The second project dealt with the characterization of a transmembrane adaptor protein PRR7. This adapter inhibits TCR signaling via down-regulation of the intracellular Lck and cell surface TCR levels. The research concerning the signaling in the environment of a multicellular organism is represented by the analysis of...
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Origin and regulation of intraepithelial CD4+CD8a+ T-cells induction by Segmented Filamentous Bacteria
Pacáková, Iva ; Dobeš, Jan (advisor) ; Štěpánek, Ondřej (referee)
Segmented filamentous bacteria (SFB) are member of mice intestinal microbiota with very unique life strategy involving tight interaction with the host's intestinal epithelium. This association with intestinal epithelial cells (IECs) induces strong immune response characterized by Th17-mediated immune response. However, recent findings revealed that SFB induce also huge accumulation of CD4+ intraepithelial lymphocytes (IELs) by the upregulation of MHCII expression on IECs in an IFN-dependent manner. Likewise to SFB, Lactobacillus reuteri was recently found to have a similar capacity of IELs induction. In contrast to SFB, L.reuteri induces IELs through the activation of the Aryl hydrocarbon receptor (AhR) by its ligands, which originate from the metabolism of tryptophan amino acid. Moreover, L.reuteri cannot induce IELs by itself and needs a complex microbiota for this induction. However, if these two bacteria can cooperate in the induction of IELs remains unknown. This thesis focuses on the interaction of SFB and L.reuteri in the context of IELs induction and investigates the contribution of each bacteria to the IELs phenotype. Data presented in my thesis indicate that SFB induce accumulation of IELs, however, interaction of SFB and L.reuteri induce full cytotoxic activation and vesicle secretion...
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Backpressure Steam Turbine
Kubiš, Zdeněk ; Ondřej, Štěpánek (referee) ; Štěpánek, Ondřej (referee) ; Fiedler, Jan (advisor)
The theme of the master’s thesis is to design a 60 MW single-casing steam turbine for the two-stage district water heating. The turbine is designed for cogeneration cycle, has four uncontrolled extractions and the outlet down to the heater. First, there is the thermodynamic calculation of the turbine operation with 100 % steam mass flow. Further, the detailed design of flow part with the strength calculation of blades and diaphragms is drawn. By the end of the thesis, the required operations are compared and corresponding heat balancing diagrams are listed. The thesis also includes a turbine longitudinal section.
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Virtualization of Public Administration Institute
Štěpánek, Ondřej ; Janoušek, Vladimír (referee) ; Neuwirth, Bernard (advisor)
This thesis deals with the virtualization of servers and computer workstations, which has recently been the cornerstone of modern data centers. The practical part is focused on selecting the most appropriate solutions for specific problems in the implementation of virtualization administration. At the same time the present work evaluates the possibility for other organizations.
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Condensation Steam Turbine for Combi-cycle
Pavlíček, Martin ; Ing.Ondřej Štěpánek (referee) ; Fiedler, Jan (advisor)
This thesis named Cosdensing steam turbine in combi-cycle deals with the calculation of thermal balancing scheme and the design of turbine. This double body steam turbine with combined HP-IP part and double-flow LP part does not have any additional samples of technological steam. LP part has two side outputs to the water-cooled condensers. There is a basic calculation of force effects on the LP part at operation. The thesis also includes a drawing of a longitudinal cut of LP part and its layout, including positron of the condensers.
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Diversity of CD8+ T-cell adaptive immune responses
Paprčková, Darina ; Štěpánek, Ondřej (advisor) ; Dobeš, Jan (referee) ; Gerrard, Audrey (referee)
CD8+ T cells are specialized immune cells that recognize and eliminate infected or malignant cells by directly attacking and destroying them. Moreover, their ability to form long-lasting memory responses ensures a rapid immune defense upon subsequent encounters with the same pathogens, making them indispensable for overall immune system function and maintaining health. Despite all of this, many aspects of their biology are still not well understood. The main objective of this thesis is to delve deeply into the adaptive immune responses of CD8+ T cells, focusing on elucidating several critical aspects. Firstly, we conducted a review and a research study of T-cell receptor (TCR) self-reactivity to understand its influence on immune responses. Intriguingly, experimental findings revealed that the degree of TCR self-reactivity did not impact the magnitude or type of the immune response. Instead, it played a decisive role in determining the fate commitment of CD8+ T cells in the periphery during homeostasis, shedding light on a nuanced regulatory mechanism. Another part of the research probed into per-cell differences of activated naïve and memory T cells. This investigation unveiled the remarkable potency of memory T cells to generate long- lived effector memory T cells. In contrast, naïve T cells...
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Signaling pathways in T-cell-mediated immunity
Janušová, Šárka ; Štěpánek, Ondřej (advisor) ; Hons, Miroslav (referee) ; Abramson, Jakub (referee)
The immune system provides protection of the host against pathogens, and tumor cells while maintaining a tolerance to self-tissues. T cells are important players in orchestrating the immune response. Helper T cells navigate other cells in the course of the immune response, cytotoxic T cells directly kill infected or altered cells, and regulatory T cells suppress the overt activation of above mentioned. T cells are activated via their antigen-specific T-cell receptor (TCR), but for proper activation, they need additional signals from co-stimulatory or inhibitory receptors. This double-step activation is one of the regulatory steps to prevent aberrant T-cell activation. The main part of this thesis is focused on understanding of the signal propagation and regulation of the T-cell signaling. We used a tandem affinity purification followed by mass- spectrometry analysis to describe the composition of the receptor signaling complex of TNFR- SF members, GITR and OX40. We employed the same method to analyze the signalosome of IL-17R. One of the described components of all the receptors is ABIN1. We generated ABIN1 knock-out mice that exhibited signs of autoimmunity and its T cells were hyperresponsive to various stimulation in vitro and in vivo. We reported ABIN1 as a regulator ot T-cell signaling. In the...
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The role of the interaction of LCK with CD4/CD8 coreceptors
Cesneková, Michaela ; Štěpánek, Ondřej (advisor) ; Černý, Jan (referee)
LCK kinase is an essential regulator of T-cell signalling that interacts with CD4 and CD8 coreceptors, which are crucial for T-cell development and T-cell lineage commitment. Their role, as well as the role of their interaction with LCK in the peripheral T cells, remains disputable, despite being studied for decades. This thesis aims to investigate the importance of LCK-coreceptor interaction in CD8+ T cell signalling and development and to determine the significance of the serine residues in LCK-mediated CD4 endocytosis. We used LCK variants bearing mutations of the coreceptor binding site or its catalytic domain in both mice and cell lines to solve this perplexity. First, the enzymatic activity of LCK variants was evaluated in this thesis. Second, we demonstrate that the function of CD8 is both, LCK-CD8 interaction dependent and independent. Then we examined the late stage of CD8+ T cell development, showing that the absence of the interaction has very mild consequences. It affects only the response of post- selection CD8 single-positive, but not double-positive, thymocytes to sub-optimal antigenic stimulation. Finally, we observed that CD4 with the mutation of all three intracellular serines to alanines shows similar LCK-dependency as wild type CD4. Overall, this study sheds light on the...
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Characterization of a novel CD8+ T-cell subset with polyamine metabolism signature
Cimermanová, Veronika ; Štěpánek, Ondřej (advisor) ; Dobeš, Jan (referee)
CD8+ T cells play a crucial role in the adaptive immune response to combat infections and tumors. Previous research into T-cell heterogeneity has revealed that subsets of antigen- experienced CD8+ T cells possess different functional properties. However, the functional diversity might already be predetermined in their naïve steady-state precursors. Recently, the Lab of Adaptive Immunity discovered a new and rare murine steady-state CD8+ T-cell subset, known as Tpam cells (CD8+ T cells with polyamine metabolism signature). Since polyamine metabolism has been linked to T-cell activation and differentiation, studying this novel subset can provide new insight into the fate of CD8+ T cells upon TCR stimulation. This diploma thesis aimed to characterize Tpam cells in terms of their origin, steady-state phenotype, fate after TCR stimulation, and potential functional role. We took advantage of various mouse models to investigate the formation of Tpam cells and found that they are dependent on a diverse TCR repertoire and are presumably formed by low-grade TCR signaling. We executed an adoptive transfer into T-cell deficient mouse model to examine their steady-state phenotype and performed an ex vivo TCR-mediated activation assay to observe their fate after activation. Our findings show that Tpam cells are...
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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin ; Vinkler, Michal (advisor) ; Tschirren, Barbara (referee) ; Štěpánek, Ondřej (referee)
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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