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Cytokine networks and their impact on the immune profile of acute myeloid leukemia (AML) patients
Ptáček, Antonín ; Musil, Jan (advisor) ; Fišer, Karel (referee)
Acute myeloid leukemia (AML) is a malignant hematological disorder characterized by aberrant expansion of blasts in the bone marrow and peripheral blood. The immune system protects the body from leukemia by eliminating transformed cells. However, in AML, the abilities of immune cells are affected both by direct contact between leukemic cells and effector cells, as well as by cytokines, metabolites and other soluble proteins that, together with the cells, form the specific AML microenvironment. The effects of cytokines and other soluble molecules in the AML microenvironment are not sufficiently described yet. This thesis aimed to optimize and implement a multiparametric flow cytometry panel for the measurement of cell populations and to implement multiparametric assays for the analysis of cytokine levels, chemokines and other soluble proteins in plasma. The following goal was to use these methods to characterize the frequency and functional phenotype of cell populations and the levels of the soluble proteins and to describe their influence on disease severity and overall survival of the patients. We also tried to find novel biomarkers of the immune escape of leukemic cells. In patients, we observed a suppressive microenvironment with aberrant levels of soluble receptors and other proteins. This...
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Bioorthogonal labelling of surface receptors on living lymphocytes
Paldusová, Kateřina ; Cebecauer, Marek (advisor) ; Benda, Aleš (referee)
The surface of cells displays high heterogeneity on chemical and geometrical levels. To understand the function of cells, we need to pay attention to the morphological features formed at the plasma membrane. To study cell surface with molecular specificity, there are plenty of imaging methods starting with the conventional wide-field microscopy through confocal microscopy, ending with super-resolution fluorescence microscopies and electron microscopies. Super-resolution microscopy studies conducted on the fixed cells provide detailed steady-state data about the cell surface nanoscopic organisation and distribution of molecules at the morphological structures. However, since cells are parts of living organisms and constantly change their properties in time and space, the information about dynamics of cellular structures and motility of molecules remains hidden when using this approach. Live-cell compatible methods are required to study dynamic changes of molecules at the single-molecule level. In this study we are focusing on the distribution and dynamics of molecules CD2 and CD4 expressed on the surface of non-stimulated T cells. The main aim of this thesis was to develop a novel method for live-cell imaging and single-molecule tracking of membrane-bound proteins in 3D and at nanoscale. With such a...
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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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Role of CD8- and CD4-Lck interactions in the signaling and development of T cells.
Horková, Veronika
Adaptive immune response plays a key role in maintaining homeostasis of the organism. T cells use an immense repertoire of T-cell receptors (TCRs) to discriminate between self and foreign antigens with very high sensitivity. Although we have many clues outlining how an ideal TCR repertoire is selected, and a good understanding of the TCR signaling machinery, there are still some key aspects of these processes that remain controversial. The objective of this thesis is to extend our knowledge of the very proximal events of TCR signaling, with special focus on interaction of TCR coreceptors with lymphocyte-specific kinase LCK. Coreceptor-LCK interaction has been described to regulate several aspects of T- cell development and response. We observed dynamic change of this interaction in course of T-cell development. Interestingly, CD4 and CD8 coreceptors displayed differential dynamics of interaction with LCK. Our data suggest that such disparity in coreceptor- LCK interaction leads to selection of more self-reactive TCR repertoire in CD8+ T cells. Moreover, when the highly self-reactive CD8+ T cells get to the periphery, the homeostatic signals drive their differentiation towards a more tolerogenic memory-like phenotype. To finally resolve the role of coreceptor-LCK interaction in the T-cell...
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The role of structural motifs in the localisation of T-cell plasma membrane proteins
Glatzová, Daniela ; Cebecauer, Marek (advisor) ; Brábek, Jan (referee) ; Rozbeský, Daniel (referee)
Plasma membrane of T cells is abundant in diverse receptors and other molecules orchestrating immune responses. Numerous studies demonstrate that the localisation of proteins in the cell is non-random and that mislocalisation either in the context of plasma membrane at nanoscale or with respect to the cell interior can lead to the protein malfunction and subsequent aberrant T- cell response. In my first Ph.D. project we focused mainly on the role of the transmembrane domain length and amino acid composition, proximal sequences and the presence or absence of palmitoylation on the localisation of transmembrane adaptor proteins LAT, PAG and NTAL in T cells. We showed that plasma membrane localisation of PAG and NTAL is controlled by the amino acid composition of their TMD and is palmitoylation independent. We propose that NTAL localisation to the plasma membrane is, despite its suboptimal length, facilitated by the electrochemical asymmetry of its TMD. Among transmembrane adaptor proteins, LAT was the most interesting one. Dependency of LAT plasma membrane localisation on palmitoylation in combination with unusual amino acid composition of its TMD led us to investigate it in a separate project. My first author Ph.D. project was thus to elucidate the role of highly conserved helix-breaking amino acids,...
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Role of CD8- and CD4-Lck interactions in the signaling and development of T cells.
Horková, Veronika ; Štěpánek, Ondřej (advisor) ; Černý, Jan (referee) ; Hons, Miroslav (referee)
Adaptive immune response plays a key role in maintaining homeostasis of the organism. T cells use an immense repertoire of T-cell receptors (TCRs) to discriminate between self and foreign antigens with very high sensitivity. Although we have many clues outlining how an ideal TCR repertoire is selected, and a good understanding of the TCR signaling machinery, there are still some key aspects of these processes that remain controversial. The objective of this thesis is to extend our knowledge of the very proximal events of TCR signaling, with special focus on interaction of TCR coreceptors with lymphocyte-specific kinase LCK. Coreceptor-LCK interaction has been described to regulate several aspects of T- cell development and response. We observed dynamic change of this interaction in course of T-cell development. Interestingly, CD4 and CD8 coreceptors displayed differential dynamics of interaction with LCK. Our data suggest that such disparity in coreceptor- LCK interaction leads to selection of more self-reactive TCR repertoire in CD8+ T cells. Moreover, when the highly self-reactive CD8+ T cells get to the periphery, the homeostatic signals drive their differentiation towards a more tolerogenic memory-like phenotype. To finally resolve the role of coreceptor-LCK interaction in the T-cell...
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Quantitative fluorescence microscopy techniques to study three-dimensional organisation of T-cell signalling molecules.
Chum, Tomáš ; Cebecauer, Marek (advisor) ; Lánský, Zdeněk (referee) ; Brameshuber, Mario (referee)
10 SUMMARY Proteins represent one of the basic building blocks of all organisms. To understand their function at the molecular level is one the critical goals of current biological, biochemical and biophysical research. It is important to characterise all aspects that affect the localisation of proteins into different compartments with specific functions, the dynamic structure of proteins and their role in multiprotein assemblies, because altering these properties can lead to various diseases. Most of the proteomic studies are nowadays performed using biochemical approaches that allow us to study multicellular organism or tissue at once. The disadvantage of these methods is complex preparation of sample and the need for a large number of cells, which leads to the loss of information at the molecular level and in individual cells. On the contrary, microscopy can provide rather detailed information about proteins of interest and at the level of a single cell. A variety of fluorescence microscopy methods in combination with recombinant DNA techniques were applied to elucidate subcellular localisation of transmembrane adaptor proteins (TRAPs) in human lymphocytes and their nanoscopic organisation at the plasma membrane. Linker of activation of T lymphocytes (LAT), phosphoprotein associated with...
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