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Targeting mitochondria to overcome resistance of breast cancer to therapy
Rohlenová, Kateřina ; Neužil, Jiří (advisor) ; Špíšek, Radek (referee) ; Vítek, Libor (referee)
(EN) Tumours are heterogeneous and consist of multiple populations of cells. The population of cells with tumour-initiating capability is known as cancer stem cells (CSC). Cells with increased stemness properties and elevated resistance to anti-cancer treatment have been shown to be highly affected upon decline of mitochondrial respiration, linking the concept of CSCs to deregulated bioenergetics. Consistently, functional electron transport chain (ETC) is crucial in tumorigenesis. Expression of HER2 oncogene, associated with resistance to treatment in breast cancer, has been connected with regulation of mitochondrial function. We therefore investigated the possibility that manipulation of mitochondrial bioenergetics via disruption of ETC eliminates the conventional therapy-resistant populations of tumour, such as CSCs and HER2high cells. We demonstrate that HER2high cells and tumours have increased complex I-driven respiration and increased assembly of respiratory supercomplexes (SC). These cells are highly sensitive to MitoTam, a novel mitochondria-targeted derivative of tamoxifen, acting as a CI inhibitor and SC disruptor. MitoTam was able to overcome resistance to tamoxifen, and to reduce the metastatic potential of HER2high cells. Higher sensitivity of HER2high cells to MitoTam is dependent on...
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Morphological, ultrastructural, and transcriptomic characterization of the newly discovered protist lineage SUM-K
Valt, Marek ; Čepička, Ivan (advisor) ; Oborník, Miroslav (referee)
Here I am presenting a novel deep-branching organism, flagellate SUM-K. SUM-K is morphologically inconspicuous protists that occurs in two distinctive forms, immotile "sun- like" form and motile, flagellated form. Sun-like cells are rounded approximately 5 µm big cells that produce numerous thin radial projections artificially resembling Heliozoeans. Based on ultrastructure analysis and light microscopy observations we classified these projections as novel type of extrusomes with putative function of prey predation. Flagellate state moves with one anterior, posterolaterally directed flagellum. The posterior end of the cell bears a long extrusion that resembles a flagellum but is not motile. Based on these morphological characteristics organism can't be classified into any of the establish eukaryotic supergroups. Likewise, phylogenetic analysis based on SSU rDNA failed to resolve its evolutionary position, placing it to relation with Ancoracysta twista, an orphan lineage similarly unclassifiable to any of current eukaryotic supergroups. Robust analysis based on 206 orthologous genes placed SUM-K to relation with Hemimastigophora. Even though the morphology of currently described Hemimastigophoreans and organism SUM-K is incongruent, its relation presents interesting prospective of evolution of...
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Mitochondria and their role in carcinogenesis
Bajzíková, Martina ; Neužil, Jiří (advisor) ; Masařík, Michal (referee) ; Mráček, Tomáš (referee)
(EN) Mitochondria are the principal intracellular organelles responsible for fuel generation; however, they are not just cell powerhouses but are involved in a range of other intracellular functions including cell metabolism, proliferation, death, and immune responses. Loss of function in mitochondria will result in oxidative stress, which is one of the underlying causal factors for a variety of diseases including cancer. Cancer cells can predominantly produce energy by glycolysis even in the presence of oxygen. This alternative metabolic behavior is known as the "Warburg Effect." Linked to this, cancer cell mitochondria can switch between glycolysis and oxidative phosphorylation (OXPHOS) for their energy requirements and survival. The electron transport chain (ETC) function is pivotal for mitochondrial respiration, which is also needed for dihydroorotate dehydrogenase (DHODH) activity that is essential for de novo pyrimidine synthesis. In our research, we have used respiration-deficient cancer cells to challenge the dogma that mitochondria with their DNA are constrained within cells in the body. Our results document that mitochondria move from normal cells within the tumor stroma to tumor cells without mitochondrial DNA (mtDNA), resulting in long-lasting recovery of mitochondrial functions and,...
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The role of mitochondrial complex II in cancer cell biology
Kraus, Michal ; Neužil, Jiří (advisor) ; Kašpárek, Petr (referee)
Mitochondria are essential organelles for most eukaryotic cells, containing intricate networks of numerous proteins. These include, among others, complexes I-IV of the electron transport chain. Being at the crossroads of the tricarboxylic acid cycle and the respiratory chain, mitochondrial complex II plays a key role in cellular metabolism. The protein complex, also known as succinate dehydrogenase, is capable of not only succinate oxidation and electron transfer but also contributes to the production of reactive oxygen species. Mitochondrial complex II consists of four subunits, SDHA-D, and four dedicated protein assembly factors SDHAF1-4 that participate in complex II biogenesis. Mutations and epigenetic modulations of genes coding for succinate dehydrogenase subunits or assembly factors are associated with pathological conditions such as neurodegenerative diseases, or may result in tumor formation. However, inborn complex-II-linked mitochondrial pathologies are rather understudied, compared to diseases with causative errors of other mitochondrial complexes, presumably due to the fact that none of complex II subunits is encoded in the mitochondrial genome. Recent studies have shown that impairment of mitochondrial complex II function or assembly leads to accumulation of alternative assembly forms...
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Effects of antidepressants and depressive disorders on mitochondrial functions
Hroudová, Jana ; Fišar, Zdeněk (advisor)
Mood disorders are serious diseases. Nevertheless, their pathophysiology is not sufficiently clarified. Biological markers that would facilitate the diagnosis or successful prediction of pharmacotherapy are still being sought. The aim of the study was to find out whether mitochondrial functions are affected by antidepressants, mood stabilizers and depression. Our research is based on recent hypotheses of mood disorders, the advanced monoamine hypothesis, the neurotrophic hypothesis, and the mitochondrial dysfunction hypothesis. We assume that impaired function of mitochondria leads to neuronal damage and can be related to the origin of mood disorders. Effects of antidepressants and mood stabilizers on mitochondrial functions can be related to their therapeutic or side effects. In vitro effects of pharmacologically different antidepressants and mood stabilizers on the activities of mitochondrial enzymes were measured in mitochondria isolated from pig brains (in vitro model). Activity of monoamine oxidase (MAO) isoforms was determined radiochemically, activities of other mitochondrial enzymes were measured spectrophotometrically. Overall activity of the system of oxidative phosphorylation was measured electrochemically using high- resolution respirometry. Methods were modified to measure the same...
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Effects of antidepressants and depressive disorders on mitochondrial functions
Hroudová, Jana ; Fišar, Zdeněk (advisor) ; Martásek, Pavel (referee) ; Kuča, Kamil (referee)
Mood disorders are serious diseases. Nevertheless, their pathophysiology is not sufficiently clarified. Biological markers that would facilitate the diagnosis or successful prediction of pharmacotherapy are still being sought. The aim of the study was to find out whether mitochondrial functions are affected by antidepressants, mood stabilizers and depression. Our research is based on recent hypotheses of mood disorders, the advanced monoamine hypothesis, the neurotrophic hypothesis, and the mitochondrial dysfunction hypothesis. We assume that impaired function of mitochondria leads to neuronal damage and can be related to the origin of mood disorders. Effects of antidepressants and mood stabilizers on mitochondrial functions can be related to their therapeutic or side effects. In vitro effects of pharmacologically different antidepressants and mood stabilizers on the activities of mitochondrial enzymes were measured in mitochondria isolated from pig brains (in vitro model). Activity of monoamine oxidase (MAO) isoforms was determined radiochemically, activities of other mitochondrial enzymes were measured spectrophotometrically. Overall activity of the system of oxidative phosphorylation was measured electrochemically using high- resolution respirometry. Methods were modified to measure the same...
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Respiration as an interdisciplinary topic in science education
Čermáková, Vendula ; Teplá, Milada (advisor) ; Distler, Petr (referee)
This diploma thesis is focused on topics of and respiratory chain and their processing as educational animations for secondary schools. In the theoretical part of the diploma thesis, supporting terms are defined (visualisations, interdisciplinary relations, animations). Next, themes are included in educational field and thematic unit in RVP G. Two analyses of the topic of respiratory chain are mentioned and evaluated in this part. Firstly, there is an analysis focused on the most used chemical and biological textbooks. The second one is focused on available online animations. For research purpose of the diploma thesis quantitative method was used - a questionnaire survey. Results of this survey are listed in the practical part. Practical part presents educational materials specified for support of education topics of respiration and respiratory chain. Stress on illustrative nature and interdisciplinarity is laid in these materials. The principal materials are educational animations which were made in program Adobe Flash Professional CS6. Study text was also written to these animations. Created educational animations give a complex view on respiratory process. These materials can be used in biology and chemistry subjects or in scientific courses. Animations include two tests giving feedback to...
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Targeting mitochondria to overcome resistance of breast cancer to therapy
Rohlenová, Kateřina ; Neužil, Jiří (advisor) ; Špíšek, Radek (referee) ; Vítek, Libor (referee)
(EN) Tumours are heterogeneous and consist of multiple populations of cells. The population of cells with tumour-initiating capability is known as cancer stem cells (CSC). Cells with increased stemness properties and elevated resistance to anti-cancer treatment have been shown to be highly affected upon decline of mitochondrial respiration, linking the concept of CSCs to deregulated bioenergetics. Consistently, functional electron transport chain (ETC) is crucial in tumorigenesis. Expression of HER2 oncogene, associated with resistance to treatment in breast cancer, has been connected with regulation of mitochondrial function. We therefore investigated the possibility that manipulation of mitochondrial bioenergetics via disruption of ETC eliminates the conventional therapy-resistant populations of tumour, such as CSCs and HER2high cells. We demonstrate that HER2high cells and tumours have increased complex I-driven respiration and increased assembly of respiratory supercomplexes (SC). These cells are highly sensitive to MitoTam, a novel mitochondria-targeted derivative of tamoxifen, acting as a CI inhibitor and SC disruptor. MitoTam was able to overcome resistance to tamoxifen, and to reduce the metastatic potential of HER2high cells. Higher sensitivity of HER2high cells to MitoTam is dependent on...
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Export of biomolecules from mitochondria
Pelc, Josef ; Doležal, Pavel (advisor) ; Kovalčíková, Jana (referee)
Mitochondrion is cellular organelle evolved from the endosymbiotic bacteria. Because of its bacterial origin mitochondrion has a number of unique properties and metabolic pathways. Mitochondria or its reduced forms are present in all eukaryotic organisms except a single exception. During the course of evolution most of mitochondrial DNA was transferred to the nucleus. Despite this, mitochondria still encode several proteins that are part of the electron transport chain and the ATP synthase. These proteins are transported from the mitochondrial matrix into the inner mitochondrial membrane. Misfolded proteins of the inner membrane are degraded by mitochondrial proteases, which leads to the release of generated peptides. Fe-S clusters are assembled in the mitochondrial matrix. Still unknown molecule, which is product of ISC pathway is transported into cytosol and participates in the assembly of cytosolic and nuclear iron-sulfur proteins. Other transport pathway ensures the exchange of lipids between the endoplasmic reticulum and mitochondria. Both mitochondrial membranes have different lipid composition. To maintain their properties specific lipid transport is required between the two mitochondrial membranes. This transport pathway is also used for the lipid synthesis in the inner mitochondrial membrane.
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Effects of antidepressants and depressive disorders on mitochondrial functions
Hroudová, Jana ; Fišar, Zdeněk (advisor)
Mood disorders are serious diseases. Nevertheless, their pathophysiology is not sufficiently clarified. Biological markers that would facilitate the diagnosis or successful prediction of pharmacotherapy are still being sought. The aim of the study was to find out whether mitochondrial functions are affected by antidepressants, mood stabilizers and depression. Our research is based on recent hypotheses of mood disorders, the advanced monoamine hypothesis, the neurotrophic hypothesis, and the mitochondrial dysfunction hypothesis. We assume that impaired function of mitochondria leads to neuronal damage and can be related to the origin of mood disorders. Effects of antidepressants and mood stabilizers on mitochondrial functions can be related to their therapeutic or side effects. In vitro effects of pharmacologically different antidepressants and mood stabilizers on the activities of mitochondrial enzymes were measured in mitochondria isolated from pig brains (in vitro model). Activity of monoamine oxidase (MAO) isoforms was determined radiochemically, activities of other mitochondrial enzymes were measured spectrophotometrically. Overall activity of the system of oxidative phosphorylation was measured electrochemically using high- resolution respirometry. Methods were modified to measure the same...
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