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NMR study of the extracellular part of the mouse Nkr-p1b receptor from natural killer cells
Skála, Kristián ; Chmelík, Josef (advisor) ; Martínek, Václav (referee)
Protein Nkr-p1b is a surface receptor of cytotoxic NK cells, that mediates inhibitory signal toward the body's own cells. In this study, the ligand binding domain of the mouse protein receptor Nkr-p1b (mNkr-p1b LBD) was prepared by recombinant expression in E. coli cells. Isolated protein was subsequently used for NMR structural analysis. Prediction of protein secondary structures ratio was carried out using three different methods (CD, PSIPRED and TALOS). Results correlate well with the structure of CTLD domain, that plays a key role in ligand binding and thus to function of Nkr-p1b receptor. We managed to prepare this protein in a form suitable for NMR experiments. Based on the data obtained by NMR spectra analysis, a preliminary model of the mNkr-p1b LBD protein structure was created. However, for more precise learning of the 3D structure accurate positions of individual atoms need to be determined by other NMR spectra evaluation in the next phase. Explaining the structure of the ligand binding domain of mNkr-p1b protein could help to better understand the complex mechanism of activation of NK cell cytotoxic activity, thereby contributing to its controlled use as a therapeutic against some viral and tumor diseases.
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Structural studies of rat NK cell receptor NKR-P1B and its ligand Clrb
Skořepa, Ondřej ; Vaněk, Ondřej (advisor) ; Kavan, Daniel (referee)
Natural killer (NK) cells are an intensively studied part of immune system possessing unique ability to recognize and induce death of tumor and virus-infected cells without prior antigen sensitization. Their function is regulated by a fine balance of signals induced by multiple activating and inhibitory cell surface receptors and their interaction with the ligands present on the target cell. This can be illustrated on the homodimeric rat inhibitory receptor NKR-P1B and its ligand Clrb which play, besides other things, crucial role in the immunological response of NK cells to the infection with rat cytomegalovirus (RCMV), one of the most studied NK cell function model in rat model organism. During RCMV infection the target cell downregulates cell surface expression of Clrb, thus decreasing inhibitory signal transmitted through the NKR-P1B receptor to the NK cell, which would ideally lead to NK cell activation and lysis of the infected cell. However, RCMV carries a gene for "decoy" surface receptor - RCTL that mimics Clrb and thus helps to escape the immunological response of NK cells. Moreover, while this escape strategy was demonstrated in the WAG rat strain, it has been shown that the NKR-P1B homologue from SD rat strain binds only Clrb and does not recognize RCTL. Thus the SD rat strain is less...
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Progesterone influence on the maternal immune system in pregnancy
Škvorová, Anna ; Koucký, Michal (advisor) ; Černý, Jan (referee)
Pregnancy represents a major challenge to the maternal immune system. From an immunological point of view, a fetus is a semi-allograft. The mechanisms providing immunological paradox of fetal tolerance are still not well known and require further research. A complex network of immuno-endocrine interactions ensures fetal growth and development within the maternal uterus. The hormone playing an indispensable role in pregnancy is progesterone. The aim of this thesis is to summarize current knowledge of the effects of progesterone on the immune system in pregnancy and its mechanisms. Progesterone can affect target cells via the classical nuclear progesterone receptors, which act as transcription factors, or it can act using a variety of other ways, including non-genomic rapid signaling. Progesterone optimizes conditions for successful establishment and maintenance of pregnancy, changes the amount, localization and characteristics of immune cells and production of cytokines. It reduces the antigen-presenting capacity of dendritic cells, monocytes, and macrophages, suppresses NK cell cytotoxicity, supports the proliferation of uterine NK and dendritic cells, affects B cells and induces the formation of T regulatory cells and their recruitment into the fetal-maternal interface. The wide range of...
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Preparation of the soluble form of a mouse NKR-P1A protein for the NMR study
Skála, Kristián ; Chmelík, Josef (advisor) ; Adámková, Lyubina (referee)
Natural killer cells (NK cells) are a type of lymphocyte. According to their function they are defined as cytotoxic cells which cause cell death without prior sensitization. NKR-P1 is one of the families of NK surface receptors. This family belong to C-type lectin like with inhibitory or activatory function. In this work we concern of soluble form of mouse protein Nkr-p1a, that is isoform of activatory receptor Nkr-p1a. This receptor is expected to be intracellular due to lack of major part of its transmembrane domain. We focus on the optimization of Nkr-p1a production parameters. As production system we used bacterial strain E. coli BL21(DE3) Gold, in which the target protein is produced and subsequently isolated in the form of inclusion bodies. Obtained recombinant protein was refolded and purified. As purification step we used high-performance liquid chromatography. We optimized concentration of inductor of expression, production time and temperature. The objective is to set up protocol for preparation of isotopically labeled protein for nuclear magnetic resonance structure characterization. (in czech)
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Production and purification of recombinant receptor Clrb
Prokopová, Tereza ; Vaněk, Ondřej (advisor) ; Černá, Věra (referee)
The Natural Killer (NK) cells play a vital role in the nonspecific immunity. They are capable of efficient immunity reaction without any antigen specific receptors on their surface. NK cells recognize non-self molecules and they also recognize their molecules serving as health markers, and absence of these molecules such as MHC glycoproteins on the target cell surface. The NK cells are able to recognize viral infection or tumor transformation in the organism. If natural killer cell is in contact with a cell carrying an abnormally low MHC class I glycoproteins, it will create a signal which informs the cell is infected with a virus. NK cells trigger apoptosis of the target cell without prior stimulation, proliferation and differentiation. They also promote inflammatory responses by the production of chemokines and cytokines. The response is always the interplay of activating and inhibitory signals that the cell receives from its surroundings. The latest research shows that the targeted modulation of NK cells leads to less complications in bone marrow transplantation. They can be potentially used in immunotherapy, e.g. in the treatment of autoimmune diseases. Therefore, NK cells are a highly-studied group of cells. This thesis is focused on a production of Clrb ("C- type-lectin-related protein b")....
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NK cell involvement in the pathogenesis of autoimmune arthritis
Richter, Jan ; Fišerová, Anna (advisor) ; Hromadníková, Ilona (referee) ; Turánek, Jaroslav (referee)
Rheumatoid arthritis (RA) is a worldwide problem representing one of the most prevalent autoimmune diseases in the world. Despite the commonness of the disea- se, its pathogenesis has not been fully described. Immune cells ranging from antigen- presenting cells to T, B and NK cells playing various roles participate in the rheumatic process. In this work we concentrated on NK cells expressing a repertoire of activating and inhibitory receptors which influence their function in health and disease. We focused on the analysis of NK cell function and described its possible modulation by rheumatic autoantigens and multivalent glycodendrimers bearing 4 (GN4C) or 8 (GN8P) N-acetyl glucosamine moieties. The effect on NK cells and the glycosylation pathways was further studied in vitro. Finally, an in vivo study was performed on an animal model of RA - col- lagen-induced arthritis (CIA) to assess the effect of the compounds on clinical develop- ment of the disease and selected immune parameters. Comparison of NK cell cytotoxicity in patients suffering from RA, other inflam- matory diseases and healthy donors showed its impairment particularly in RA patients. Peripheral blood NK cells reacted to GN8P glycoconjugate by inhibition of their effector function in CD161 high-expressing samples. The MGAT5...
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Preparation and study of human NK cell receptor AICL
Nový, Jiří ; Vaněk, Ondřej (advisor) ; Novák, Petr (referee)
Natural killer cells, or NK cells are an integral component of innate immunity and fullfills the function of recognizing and killing tumor and virus-infected cells. Their function is regulated by signals produced by the interaction of inhibitory and stimulatory receptors on their surface with their specific ligands on the targer cell surface. NKp80 is an activating receptor of NK cells and forms specific complex with cell receptor AICL, both of which belong to the family of C-type lectin-like receptors. Overexpression of AICL receptor is preferably specific for tumor cells of myeloid character. This master's thesis describes the production of AICL mutated form by expression in Escherichia coli BL21 Gold (DE3) followed by isolation and in vitro renaturation of the target protein. In a previous study it was found that an odd number of cysteines in the extracelular lectin domain of AICL causes wrong folding of the protein. Substituting an odd cystein for serine at position 87 lead to stable soluble form of AICL with an even number of cysteines in conserved positions, typical for CTLD receptors. Correctness of the formation of disulfide bonds between cysteines was verified by mass spectrometry. Significant amount of the protein gained allowed for setting up a wide variety of crystallization conditions....
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Lectin receptor-ligand interaction important in experimental tumor therapy
Grobárová, Valéria ; Černý, Jan (advisor) ; Filipp, Dominik (referee) ; Krulová, Magdaléna (referee)
Lectin-saccharide interactions are involved in many biological processes essential for the survival and proper function of multicellular organisms. C-type lectin-like receptors, predominantly expressed by cells of the innate immune system, recognize saccharide structures on microbes and also aberrant glycosylation pattern of cancer cells. The NKR-P1 receptor family was among the first natural killer (NK) receptor families that were identified, however ligands for some of members remain still elusive. Recently, publications describing N-acetylglucosamine-terminated oligosaccharide structures as possible ligands for NKR-P1 receptor have been subjects for correction/retractions after investigation of the Ethical Committee of the Institute of Microbiology, ASCR, v. v. i. and Charles University in Prague. Re-evaluation of glycodendrimer effect, particularly effect of N-acetyl-D-glucosamine octabranched dendrimer on polyamidoamine scaffold (GN8P), revealed mostly indirect role of NK cells on modulation of immune responses. Properly folded soluble recombinant rat NKR-P1A and mouse NKR-P1C lack binding activity to neoglycoproteins modified with GlcNAc-terminated structures. Moreover, new possible target cell populations (NKT cells and macrophages) for saccharide binding were identified.
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Studies on structure and biological functions of NKR-P1 receptors
Rozbeský, Daniel ; Novák, Petr (advisor) ; Konvalinka, Jan (referee) ; Drbal, Karel (referee)
Natural killer (NK) cells play a significant role in the detection and destruction of virally infected and tumor cells. The NKR-P1 receptors regulate NK cell function by an alternative missing-self recognition system. Although the NKR-P1 receptors were among the first surface NK receptors identified on rodent NK cells more than 20 years ago, there is still very little known about their biological function and their physiological ligands. Furthermore, no three-dimensional structure of any of the NKR-P1 family receptors has been published so far. To understand the functional architecture of mouse NKR-P1 receptors, we developed a simple and efficient protocol providing large amounts of pure soluble NKR-P1 proteins. The crystal structure of mouse NKR-P1A, determined at 1.7 A resolution, is the first structure of a representative of the NKR-P1 family. Crystal structure is formed by a compact C-type lectin-like domain and an extended loop that participates in domain swapping. A potential role of the swapped loop has been suggested in natural ligand binding by in silico studies. However, chemical cross-linking and H/D exchange in combination with high resolution mass spectrometry revealed this loop in close proximity to the compact core in solution. The discrepancy between the crystal and solution structure...
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NK cells and their receptors in immune regulation - possible targets for immunomodulation
Svoboda, Jan ; Fišerová, Anna (advisor) ; Pěknicová, Jana (referee) ; Kročová, Zuzana (referee)
(english) Natural Killers - NK cells play an important role in immune surveilance and regulation either by direct cytotoxicity towards infected, transformed or otherwise damaged cells, or by production of cytokines and chemokines. The resulting response of NK cells is given by the sum of stimulating and inhibiting signals, tranduced by a wide array of receptors. Killer Ig-like receptors KIR2DL4 and LILRB1, which recognize self HLA-G molecules in pregnancy, as well as NKR-P1 receptors, which differ in the number of isotypes, are species-dependent and reduced during phylogenesis. NKG2D, reacting to stress-inducible proteins, and adenosine receptors (AR), which supress the inflamatory reaction, remain evolutionary conserved. The aim of this work was to study the involvement of NK cells and their receptors in several immune disorders and in various species, to provide new insights into their function and posisible immune modulation. We have shown here, that the choice of species in the study of NK cell effector functions may be crucial in some cases. The reaction to glycans, using synthetic GlcNAc-terminated glycomimetics GN8P, exerted opposing effects on NK cell function in humans and C57Bl/6 mice. In humans, the glycomimetic decreased cytotoxic activity of high NKR-P1A expressing NK cells, while in...
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