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Structural studies of selected protein complexes involved in signal transduction
Honzejková, Karolína ; Obšil, Tomáš (advisor) ; Bouřa, Evžen (referee) ; Pavlíček, Jiří (referee)
Protein-protein interactions are critical for most physiological and pathophysiological processes. Detailed characterization of these interactions is therefore essential not only to understand the nature of these events, but also to design strategies to target these interactions. This work focuses on the study of the structure and interactions of several proteins and their complexes. Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAP3K) that activates the p38/JNK protein kinase pathways, thereby directing cells toward an inflammatory response or apoptosis. ASK1 interacts with thioredoxin (TRX), a small dithiol oxidoreductase, which inhibits ASK1, but the mechanism of this inhibition has not been clarified. CaMKK1 and CaMKK2 are Ca2+ /calmodulin (CaM)-dependent protein kinases that regulate cellular energy balance, memory, and inflammation, among others. Both are inhibited by 14-3-3 proteins, but despite their domain and sequence similarities, the extent of 14-3-3 protein- mediated inhibition is different. Estrogen receptor alpha (ERα) is a nuclear receptor involved in breast cancer. Tamoxifen, an ERα antagonist, is used to treat this disease, but resistance often develops. 14-3-3 proteins interact with ERα and inhibit its transcriptional activity,...
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Characterization of pancreatic beta cells after their in vitro proliferation induced by synthetic modified mRNA
Veľasová, Adriana ; Koblas, Tomáš (advisor) ; Černá, Věra (referee)
The origin and development of type I. and II. diabetes mellitus is directly related to homeostasis of proliferation and apoptosis of pancreatic β-cells. Any imbalance that leads to a decrease in the number of β-cells consequently increases the pro- bability of developing this disease. Patients suffering from diabetes mellitus are de- pendent on partial or complete exogenous insulin replacement, as their pancreas is unable to meet the body's insulin needs. Therefore a need for restoration of normal β-cell mass in diabetic patients leads to the attempts to develop new therapeutic approaches that could expand remaining β-cells of the organism and restore phys- iological insulin production. A major obstacle in this regard is a low sensitivity of terminally differentiated β-cells to mitogenic stimuli that could induce the entry of β-cells into the cell cycle. Activation of β-cell proliferation is associated with the G0/G1/S cell cycle transi- tion, which is under the control of retinoblastoma protein (RB). In order to activate cell cycle entry RB must be phosphorylated. RB phosphorylation is provided by specific cell cycle regulators, particularly cyclin-dependent kinases 4 and 6, which associate with family D cyclins. In accordance with the aim of this Diploma thesis, the effect of these cell cycle...
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Plant alkaloid sanguinarine and its derivatives
Tůmová, Lucie ; Stiborová, Marie (advisor) ; Hýsková, Veronika (referee)
This work is summarizing actual knowledge about sanguinarine and quaternary benzo[c]fenanthridine alkaloids. The quaternary benzo[c]fenanthridine alkaloids were found in roots plants Sanguinaria canadensis and Macleaya cordata. This plants are used in tradicional Chinese medicine for its antimycotic, antibacterial and anti-inflammatory activities since antiquity. Regarding to possibility quaternary benzo[c]fenanthridine alkaloids to induce apoptosis these investigated such as possible agents for cancer treatment. The quaternary benzo[c]fenanthridine alkaloids interact with DNA and proteins. They are able to intercalate to the DNA. The alkaloids can be used like fluorescence DNA probe. Metabolism by sanguinarine and next quaternary benzo[c]fenanthridine alkaloids has not yet completely determinated. The first step sanguinarine detoxication is its conversion to less toxic dihydrosanguinarine. Sanguinarine oxidation is mediated by cytochrome P450 1A1. Key words: Quaternary benzo[c]fenanthridine alkaloids, sanguinarine, apoptosis, intercalate, heterogenous substances, enzymes, cytochrom P450
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Analysis of the pathways responsible for the resistance of leukemic cells towards L-asparaginase
Šimčíková, Markéta ; Konvalinka, Jan (advisor) ; Poljaková, Jitka (referee)
Acute lymphoblastic leukaemia (ALL) is the most frequent malignancy in childhood. Despite the very successful ALL therapy, relapses occur to 15-20 % of children. One of the possible relaps causes is the resistance to therapeutics. ALL is treated with combined chemotherapy in which cytostatic agent L-asparaginase plays the essen- tial role. L-asparaginase depletes extracellular asparagine and glutamine. Antagonist of the L-asparaginase is asparagine synthetase enzyme, which synthesizes the cellular asparagine. The specific antileukaemic effect of L-asparaginase is believed to be thanks to lower activity of the asparagine synthetase in leukaemic cells comparing to the healthy cells. The asparagine and glutamine deficiency harms the cellular proteosyn- thesis and induces apoptosis. Mechanism of the L-asparaginase cytotoxic effect and mechanism of corresponding resistance is still not fully explained. This bachelor thesis is a part of a project studying mechanisms of leukaemic cells resistance to L-aparaginase. In the model leukaemic REH cell line a deletion del(5)(q34) was discovered, which cannot be found in the resistant clone of these cells. This thesis focuses on proving different sensitivity of leukaemic cells, with or without the deletion, to L-asparaginase. The limiting dilution was used to obtain...
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The influence of acyclic nucleotide phosphonates PMEG and PMEDAP on p38 kinase signaling in human leukemic cells
Nejedlá, Michaela ; Entlicher, Gustav (advisor) ; Slaninová, Jiřina (referee)
PMEG [9-(2-phosphonomethoxyethyl)guanine] and PMEDAP [9-phosphonomethoxy- ethyl)-2,6-diaminopurine] are acyclic nucleoside phosphonates possessing cytotoxic properties. Antiproliferative effect of PMEG was demonstrated in various tumor cell lines in vitro. PMEG also represents an active component of some experimental prodrugs with enhanced selectivity and efficacy (such as GS-9219). PMEDAP seems to have weaker effect in vitro compared to PMEG, however it exhibited pronounced antitumor effect in SD-rats with spontaneous lymphoma. Therefore it was included in the present study as well. The aim of this study was to describe the interactions of PMEG and PMEDAP with p38 MAP kinase signaling and its relationship to the apoptosis. We investigated the influence of these compounds on the expression of four genes encoding p38 MAPK isoforms and whether this change is translated into the protein. It was found that PMEG up-regulates p38β and γ mRNA in CCRF-CEM cells and p38 β and δ in HL-60 cells. The effect of PMEDAP was less pronounced than that of PMEG. However, total p38 protein level remained unaffected by PMEG and PMEDAP. Activation of p38 MAPK cascade was also measured in the cells exposed to these agents using phospho-specific antibodies. We found that neither PMEG nor PMEDAP activated p38 kinase...
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The role of protein kinase C and its targets in cardioprotection
Holzerová, Kristýna ; Hlaváčková, Markéta (advisor) ; Alán, Lukáš (referee) ; Vízek, Martin (referee)
The mortality of cardiovascular diseases remains high and it likely tends to increase in the future. Although many ways how to increase the resistance against myocardial ischemia- reperfusion damage have been described, few of them were transferred into clinical practice. Cardioprotective effect of chronic hypoxia has been described during 60s of the last century. Its detailed mechanism has not been elucidated, but a number of components has been identified. One of these components presents protein kinase C (PKC). The role of PKC was described in detail in the mechanism of ischemic preconditioning, but its involvement in the mechanism of cardioprotection induced by chronic hypoxia remains unclear. One reason is the amount of PKC isoforms, which have often contradictory effects, and the diversity of hypoxic models used. The most frequently mentioned isoforms in connection with cardioprotection are PKCδ and PKCε. The aim of my thesis was to analyze changes in these PKC isoforms at two different cardioprotective models of hypoxia - intermittent hypobaric (IHH) and continuous normobaric hypoxia (CNH). We also examined the target proteins of PKCδ and PKCε after the adaptation to IHH, which could be involved in the mechanism of cardioprotection. These included proteins associated with apoptosis and...
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Carbohydrate dimers in tumor immunotherapy
Krupová, Monika ; Bezouška, Karel (advisor) ; Ryšlavá, Helena (referee)
Carbohydrate dimers in tumor immunotherapy Monika Krupová (Department of Biochemistry, Faculty of Science, Charles University in Prague) One possible approach to tumor immunotherapy is an activation of killer lymphocytes through specific ligands for their surface receptors. CD69 is a molecule greatly widespread among various cells of haematopoietic origin. Since the physiological ligand for this receptor is still unknown, ligand mimetics are used for modulation of its activity. The mimetics tested in this work are based on monomeric or oligomeric carbohydrated attached through two different chemical groups to the central linker of varying length, giving rise to thiourea and triazole series. The ability to precipitate soluble NKR-P1 and CD69 receptors was evaluated in precipitation assays and the optimal length of the linker for NKR-P1 receptor was found to be decyl. On the other hand, cross-linking of CD69 is not so dependent on the length of the linker. The aim of this work was to describe in vitro effect of the tested compounds on cellular signalization, natural killing of leukemic cell lines and activation-induced apoptosis. Compounds of triazole series containing two disaccharides (GalNAc β1→4 GlcNAc) linked by a linker were found to have the strongest effect on the production of...
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Immunological testing of combined LELTE / saccharide dendrimers
Kádek, Alan ; Bezouška, Karel (advisor) ; Man, Petr (referee)
Immunological testing of combined LELTE / saccharide dendrimers. (in Czech) Alan Kádek (Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic) CD69 is a widespread receptor of the immune system cells. Although a physiological ligand for this receptor is still unknown, in Laboratory of protein architecture its affinity towards a range of compounds including calcium, carbohydrates and charged compounds such as carboxylated calixarenes, has been proved. Moreover, a pentapeptide sequence LELTE derived from a mycobacterial chaperonine protein hsp65 has been recently identified as a ligand for CD69 representing a "danger" signal for the immune system. However, this peptide is not immunoactive per se, but only after its presentation within the multivalent environment of its parent protein, or after artificial dimerization using bi- or polyfunctional reagents. In this thesis I evaluate for four newly synthesized compounds their in vitro immunological effects on cellular signalization, proliferation, natural killing of tumors and on induction of apoptotic cell death in immunocytes. The tested compounds present LELTE peptide through attachment to a cyclopeptidic RAFT scaffold (K-K-K-P-G)2 through the ε-amino groups of lysine residues, alone or in combination with a...
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The role of protein kinase C and its targets in cardioprotection
Holzerová, Kristýna ; Hlaváčková, Markéta (advisor) ; Alán, Lukáš (referee) ; Vízek, Martin (referee)
The mortality of cardiovascular diseases remains high and it likely tends to increase in the future. Although many ways how to increase the resistance against myocardial ischemia- reperfusion damage have been described, few of them were transferred into clinical practice. Cardioprotective effect of chronic hypoxia has been described during 60s of the last century. Its detailed mechanism has not been elucidated, but a number of components has been identified. One of these components presents protein kinase C (PKC). The role of PKC was described in detail in the mechanism of ischemic preconditioning, but its involvement in the mechanism of cardioprotection induced by chronic hypoxia remains unclear. One reason is the amount of PKC isoforms, which have often contradictory effects, and the diversity of hypoxic models used. The most frequently mentioned isoforms in connection with cardioprotection are PKCδ and PKCε. The aim of my thesis was to analyze changes in these PKC isoforms at two different cardioprotective models of hypoxia - intermittent hypobaric (IHH) and continuous normobaric hypoxia (CNH). We also examined the target proteins of PKCδ and PKCε after the adaptation to IHH, which could be involved in the mechanism of cardioprotection. These included proteins associated with apoptosis and...
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Mechanism of anti-cancer activity induced by sesquiterpene lactones.
Filandr, František ; Novák, Petr (advisor) ; Grobárová, Valéria (referee)
One way to stop tumor growth in organism is to induce differentiation, apoptosis or necrosis of tumor cells. A class of chemicals known to induce apoptosis and inhibit proliferation in leukemia cells are sesquiterpene lactones. One of these lactones is cnicin, a bitter tonic used in liqueurs, found in the plant Cnicus benedictus. The mechanism of this inhibition, is not fully understood but certain signaling pathways are suspected, mainly the recently discovered Hippo signaling pathway which controls the organ size and apoptosis in mammalian cells. The core kinase of this signaling pathway is MST1/2 protein and its activation by sesquiterpene lactone cnicin resulting in cleavage of its active N-terminal domain is observed in this work. Also, the effect of cnicin on down-regulating main oncoprotein deregulated in leukemia cells C-MYC is studied. In addition the results of q-PCR also show significant down-regulation of anti-apoptotic BCL2 and MCL1 genes and cMYC oncogene. (In Czech)
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