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The importance of lipid composition of membranes for the development of Alzheimer's disease
Novotná, Natálie ; Rudajev, Vladimír (advisor) ; Hanousková, Barbora (referee)
Lipids are an essential components of cell membranes and their homeostasis plays an important role in the development of Alzheimer's disease. The aggregation and neurotoxic effects of amyloid β, mainly Aβ42, on the neural cell membrane are crucial for pathological changes in the brain tissue which leads to its degeneration and loss of cognitive functions. The complex relationship between amyloid β and lipids is also supported by fact that membrane lipids do not only support the amyloid binding to the membrane, but also they regulate the splicing of the amyloid precursor protein, therefore the biosynthesis of β amyloid. The most important binding partners of Aβ42 include gangliosides, especially the ganglioside GM1, but also sphingomyelin and cholesterol. In contrast, glycerophospholipids primarily affect the process of the protein production.
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The characterization of blood platelet cellular prion protein
Broučková, Adéla ; Holada, Karel (advisor) ; Matěj, Radoslav (referee) ; Suttnar, Jiří (referee)
The conformational conversion of the cellular prion protein (PrPc) to the misfolded isoform (PrPsc) is the central pathogenic event in the transmissible neurodegenerative prion diseases. The recently shown transmissibility of variant Creutzfeldt-Jakob disease by blood transfusion emphasizes the need for better understanding of the PrPc in blood. In the current thesis, we focused on blood platelet PrPc, which has not been very well described so far. In the first part of the thesis, platelet PrPc was characterized as glycosylphosphatidylinositol- anchored glycoprotein with dominant diglycosylated form. Platelet PrPc was shown to be sensitive to cleavage with proteinase K, which is a feature discriminating between cellular and pathological prion protein. We have confirmed that platelet PrPc binds copper ions by its N- terminal octapeptide repeat region. Regarding quantity of PrPc molecules expressed on blood elements we have proved that both platelets and red blood cells express considerable amount of PrPc and thus can not be neglected in the problematic of prions transmission by blood transfusion. The detailed study regarding PrPc localization in blood platelets is presented in the second part of the thesis. PrPc was shown to be expressed in -granules as well as on the cytoplasmic membrane of...
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Trafficking of purinergic P2X receptor in eukaryotic cell
Pražák, Šimon ; Tvrdoňová, Vendula (advisor) ; Kolář, David (referee)
Purinergic receptors are membrane ion channels activated by extracellular ATP. In vertebrates, seven genes encoding P2X subunits was found. These subunits are designated as P2X1 - 7. Every P2X receptor subunit consists of two transmembrane domains, extracellular domain and intracellular N- and C- termini. P2X receptors fold to homo- or heterotrimers. P2X receptors have a wide distribution in the organism, functional receptors are found in neurons, glial cells, muscle cells and also in nonexcitable tissues as epithelial, endothelial, and in hemopoietic tissue. Purinergic signalling plays an important role in pain transmission, CNS injury and immune processes. P2X receptors are synthesized on the rough endoplasmic reticulum and are transported to the plasma membrane after post-translational modifications in the Golgi apparatus. The distribution and transport of P2X receptors is subunit specific and dependent on the cell type in which they are expressed. P2X receptors can be divided into three groups according to the way they are moved in the cell, which differ in transport speed, plasma membrane accumulation rate and rate of internalization.
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Identification of a new mechanism of Lck regulation via its C-terminal sequence
Valečka, Jan ; Filipp, Dominik (advisor) ; Vomastek, Tomáš (referee)
T-cell activation is a complex process crucial for a proper function of immune system. It has been extensively studied and its main features are well understood. However, some of the events involved in T-cell signalling are still unclear. After T-cell receptor stimulation, Src-family kinase Lck drives the initiation of signalling by tyrosine phosphorylation. Phosphorylation of several downstream targets is dependent on the redistribution of Lck to the different compartment of the plasma membrane, called lipid rafts. In lipid rafts, active Lck is juxtaposed and activates raft-resident substrates which then trigger downstream signalling. The critical in this process is the mechanism of Lck translocation to lipid rafts which has not been studied so far and represents the topic of great academic and clinical interests. Previously, we identified the adaptor protein RACK1 as a candidate protein mediating the redistribution of Lck to lipid rafts by linking it to the microtubular network. In this thesis, we analysed the structural features and functional role of RACK1 in its interaction with Lck. We show here, using the SYF cell lines expressing the wild type and various mutated forms of Lck, that intact SH3 or SH2 domains of Lck are required for an effective RACK1-Lck complex formation. We also documented...
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Functional activity of opioid receptors in membrane domains
Cechová, Kristína ; Hudeček, Jiří (advisor) ; Mrízová, Iveta (referee)
7 ABSTRACT In this Thesis, we examined the influence of morphine administration to the laboratory rats on the amount of µ-opioid receptors and caveolins in their cerebral cortex. Effect of morphine is known to be caused by its binding to opiod receptors, in particular to the µ subtype, and a long-term exposure to morphine reduces the functionality and number of these receptors as part of the resulting tolerance and addiction. Caveolins are proteins essential for formation of the membrane microdomains of caveolae, although it is known today that presence of these proteins is not limited to caveolae and their function is probably independent of these domains (they may participate in the regulation of cell signaling pathways, lipid transport, etc.). The function of caveolins in brain cells is not precisely known yet. In the experimental part of this work, we used the Western blot method to estimate the presence of caveolin-1 and caveolin-2 in the cerebral cortex of the rats after ten-days morphine application and in control animals. A significant increase of caveolin-1 was observed after morphine treatment as compared to control animals; a smaller, non-significant increase of caveolin-2 was also found. The amount of μ-opioid receptors in morphine affected animals was significantly decreased compared to...
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The characterization of blood platelet cellular prion protein
Broučková, Adéla ; Holada, Karel (advisor) ; Matěj, Radoslav (referee) ; Suttnar, Jiří (referee)
The conformational conversion of the cellular prion protein (PrPc) to the misfolded isoform (PrPsc) is the central pathogenic event in the transmissible neurodegenerative prion diseases. The recently shown transmissibility of variant Creutzfeldt-Jakob disease by blood transfusion emphasizes the need for better understanding of the PrPc in blood. In the current thesis, we focused on blood platelet PrPc, which has not been very well described so far. In the first part of the thesis, platelet PrPc was characterized as glycosylphosphatidylinositol- anchored glycoprotein with dominant diglycosylated form. Platelet PrPc was shown to be sensitive to cleavage with proteinase K, which is a feature discriminating between cellular and pathological prion protein. We have confirmed that platelet PrPc binds copper ions by its N- terminal octapeptide repeat region. Regarding quantity of PrPc molecules expressed on blood elements we have proved that both platelets and red blood cells express considerable amount of PrPc and thus can not be neglected in the problematic of prions transmission by blood transfusion. The detailed study regarding PrPc localization in blood platelets is presented in the second part of the thesis. PrPc was shown to be expressed in -granules as well as on the cytoplasmic membrane of...
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The function of palmitoylation of membrane proteins in immune cells
Hanusová, Zdeňka ; Otáhal, Pavel (advisor) ; Pavlů, Barbora (referee)
Protein palmitoylation is a post-translation modification, which typically regulates the protein interaction with a membrane; apart from that, it can have various functions in protein regulation. Process of this modification covers covalent attachment of palmitate to an aminoacid residue in the target protein; identity of the aminoacid than determines the palmitoylation type. Most common is modification of a cystein residue - in that case we speak about so-called S-palmitoiyation. The exceptionality of this lipid modification type is in the reversibility of the whole process; this enables for example trafficking regulation of many proteins between various membrane compartments and ragulation of proteins' function. In vivo, palmitoylation of many proteins is mediated by enzymes protein acyltransferases, while depalmitoylation is mediated by enzymes acylprotein thioesterases. Palmitoylated proteins can be identified in wide spectrum of cellular types, also in immune cells. Palmitoylation plays here an important role, especially in interaction of signal proteins with lipid rafts and the related modulation of protein's function. Significance has palmitoylation also as a dynamic process, which mediates the right identification of protein's subcellular localization. This work is a review and it's aim is...
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