Search

NK cells play a key role in the defence against cells that have been infected by a virus, a protozoan or have undergone malignant transformation. In addition, they also regulate the activity and quantity of other cells of the immune system. Target cells are recognized using their activating and inhibitory receptors, from which they receive activating and inhibitory signals, on which the cytotoxic response of NK cells depends. There is a dynamic balance between the signals that determines the life and death of the target cell. If activation signals prevail, the target cell will be eliminated. If inhibitory signals prevail, then a cytotoxic response will not be triggered. The NKp30 receptor, which belongs to the immunoglobulin-like receptor superfamily, is an important activating receptor that recognizes a number of ligands, including hemagglutinin of vaccinia and ectromelia virus, human cytomegalovirus pp65 protein, B7-H6, BAG-6, and galectin-3. The extracellular domain of the NKp30 receptor is capable of homooligomerization in solution under certain conditions. The first requirement is the presence of N-glycosylation, the second requirement is the presence of a 15 amino acid long "stalk" domain that connects the ligand binding domain with the transmembrane α-helix. The aim of this thesis was to...

Natural killer cells are part of innate immunity and play a key role in defending the organism. Their role in the defense against tumors and anti-tumor therapy has been the subject of multiple research projects because tumors are among the most frequent causes of death worldwide. Tumor therapy is often complicated and invasive; therefore, finding new therapeutic approaches that target naturally occurring defense mechanisms is advantageous. One of the key mechanisms used by NK cells to recognize tumor cells and eliminate them is signaling via their receptor NKp30. The binding of an activation ligand to this receptor can induce the activation of a cytotoxic response, leading to the elimination of the tumor cell. One of the activating ligands that can bind to NKp30 is B7-H6, a cell surface protein found on certain types of tumors. However, the interaction between B7-H6 and NKp30 has not been wholly described yet. This thesis focuses on different methods, which can be used for obtaining the B7-H6 domain bearing a fluorescent label, that could be used to visualize NKp30 on the cell surface, thus allowing for further description of the interaction between these molecules. KEY WORDS NK cells, NKp30, B7-H6, sortase A, HEK293

Natural killer cells are large granular lymphocytes of innate immunity that are characterized by the ability to kill cancer and virus-damaged cells without prior activation. Cytotoxic functions of NK cells are regulated on the one hand through surface receptors recognizing MHC-I molecules, on the other hand by the presence of a set of activating and inhibitory receptors that are under normal conditions in balance with each other. Therefore, the fate of the target cell depends not only on the expression of MHC-I, but also on the expression of ligands that activate NK cell receptors. One of the activating receptors of NK cells is NKp30. Three specific cellular ligands have been discovered for NKp30: human BCL-2-associated athanogen 6 (BAG-6, also known as BAT3), tumour antigen B7-H6, and the newly discovered ligand galectin-3. All these ligands are often expressed by cancer cells, where BAG-6 and Gal-3 inhibit NK cell functions, which may be a mechanism for tumour escape from the immune system. Therefore, Gal-3 is a new potential drug target that, by inhibiting Gal-3, can help the immune system defend itself against malignantly transformed cells. This bachelor's thesis includes the verification of the effect of the Cys173 - Ser173 mutation in the carbohydrate recognition domain of galectin-3 on the...

NK cells are an essential part of the immune system. They are the so-called natural killers and carry several receptors on their surface. Two types of receptors are crucial for immune surveillance, according to their function, called inhibitory and activating. Inhibitory receptors provide auto-tolerance. The second type is activating receptors, whose activation signals toward initiating a cytotoxic response or involving other immune system components (e.g., macrophages). The activating receptor NKp30 (also known as NCR3 or CD337) is a protein of the Natural Cytotoxicity Receptors (NCR) family. It is one of the primary human NK cell activating receptors with potential use in targeted anticancer therapy. NKp30 has an activating ligand protein B7-H6, which is not found on the surface of healthy cells. It is exclusively found on highly stressed cells, e.g., infected or malignantly transformed cells. If a malignantly transformed cell carries B7-H6 on its surface, in most cases, it is recognized and eliminated almost at its formation. Not all tumour cells are B7-H6 positive, so it is possible to visualize them to the immune system through surface decoration with B7- H6. Moreover, such a ligand can be modified to amplify the immune response. This work is based on Pekar L. et al. (2020) publication, which...

NK cells, the cells of non-adaptive imune system, are able to recognise viraly infected or oncogenous cells by many inhibiting and activating receptors that are expressed on their surface and eliminate them consequently. For NKp30, activating receptor of NK cells included in NCR (Natural Killer Cell Receptors) family, lately there were identified several ligands, including membrane protein B7-H6 expressed on oncogenous cells surface and BAG- 6, cell core protein with wide spectrum of functions. Aim of this thesis was preparation of expression vectors coding for receptor NKp30 and his ligands B7-H6 and BAG-6, enabling expression of these proteins in HEK293 cell line. Keywords: NK cell, plasmid, receptor, NKp30, B7-H6, BAG-6

NK cells (natural killer cells) play a key role in innate immunity. Their function is to recognize and kill infected, stressed or malignantly transformed cells. A range of surface receptors promotes this recognition. Cytotoxic mechanisms, lead to induction of apoptosis in the target cell. Receptor NKp30 is one of cytotoxic reaction triggers. It belongs, with NKp46 and NKp44, to NCR (natural cytotoxicity receptors) family. This work describes preparation of NKp30 receptor with natural and simple glycosylation in expression system of human embryonic kidney cell line 293 (HEK293). It was found that glycosylated receptor NKp30 forms noncovalent oligomers. Equilibrium is formed in solution between oligomers and monomers. Oligomerization depends on glycosylation, deglycosylated protein doesn't form oligomers. A recombinant endoglycosidase ENDO F1 was prepared for purposes of deglycosylation.