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Study of expression and maturation of mitochondrial oxidative phosphorylation system during mammal's prenatal period
Mrhálková, Andrea ; Hůlková, Martina (advisor) ; Ješina, Pavel (referee)
Postnatal adaptation of neonate to extrauterine life is among others dependent on maturation of mitochondrial oxidative phosphorylation system (OXPHOS). It depends on effective mitochondrial biogenesis during fetal developement. The inadequate capacity of mitochondrial OXPHOS system plays an important role in the neonatal mortality and morbidity. Therefore the study of mitochondrial biogenesis on molecular and biochemical level is important to improve the care of very premature neonates, especially critically ill premature neonates. This thesis has been worked out in The laboratory for study of mitochondrial disorders (Department of Pediatrics, 1st Faculty of Medicine, Charles University in Prague). The thesis is based on molecular genetic analyses, which are focused on characterisation of ATP synthase gene expression and on changes in mitochondrial DNA content during human and rat fetal development. The results provide the better insight into mitochondrial respectively ATP synthase biogenesis during human and rat fetal development.
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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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Molecular mechanisms of tamoxifen resistance in breast cancer
Tomková, Veronika ; Truksa, Jaroslav (advisor) ; Brábek, Jan (referee) ; Mráček, Tomáš (referee)
The resistance to tamoxifen, a drug used in the adjuvant therapy for hormone sensitive breast cancer, represents a major clinical obstacle. Although various mechanisms leading to tamoxifen resistance have been described and intensively studied, a significant number of patients still become resistant to the treatment and eventually relapse. Tamoxifen therapy has been shown to enrich tumors with cancer stem cells (CSCs), which are naturally resistant, and have self-renewal ability and the potential to form secondary tumors. Metabolic rewiring, altered iron metabolism and upregulation of ATP-binding cassette (ABC) transporters have been shown to be important in the maintenance of CSC phenotype. Therefore, we investigated these mechanisms as possible contributors to tamoxifen resistance in vitro in two tamoxifen resistant (Tam5R) cell lines that we established. We show that Tam5R cells have dramatically disassembled and less active mitochondrial supercomplexes (SCs) and higher level of mitochondrial superoxide, together with a fragmented mitochondrial network. Such dysfunction of mitochondria results in the AMP-activated protein kinase (AMPK) activation and metabolic rewiring towards glycolysis. Importantly, cells lacking functional mitochondria are significantly more resistant to tamoxifen, supporting...
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Tumor suppressor NDRG1 and its regulation by iron chelators
Vondráčková, Michaela ; Truksa, Jaroslav (advisor) ; Brábek, Jan (referee)
Iron is an essential trace element required for many processes within a cell, including DNA synthesis and cell cycle progression. Moreover, it is critical for cellular respiration in mitochondria. Due to their proliferative nature, cancer cells are dependent on iron, and depleting this element via iron chelators results in the inhibition of ribonucleotide reductase, leading to cell cycle arrest and apoptosis of cancer cells. Recently, an alternative mechanism for the effect of iron chelators have been proposed, including induction of N-myc downstream regulated gene 1 (NDRG1) expression and its inhibitory effect on c-MET, EGFR, and NF-κB pathways, which can act as oncogenes in a certain context. NDRG1 is a tumour suppressor gene, which is downregulated in many cancers and its downregulation correlates with cancer progression, poor differentiation, and higher metastatic potential. It has been shown that NDRG1 expression can be regulated by intracellular iron - a decrease in intracellular iron leads to upregulation of NDRG1 at mRNA and protein level via the HIF-1-dependent mechanism by inhibiting prolyl hydroxylases. Recently, we have conceived the concept of mitochondrially targeted chelators as an effective anti-cancer agent and in this work, we focused on the evaluation of mitochondrially targeted...
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Mitochondrial respiration of brown adipose tissue in development of cold acclimation
Galatík, František ; Žurmanová, Jitka (advisor) ; Holzerová, Kristýna (referee)
Historical experiments regarding the influence of low ambient temperatures were often accompanied with the development of detrimental effects. Our laboratory recently published a protocol of mild cold acclimation (5 weeks in 8 ± 1 řC) which induces cardioprotective phenotype in rats (Rattus norvegicus). An important mechanism of cold acclimation is the activation and increase of brown adipose tissue. Besides the nonshivering thermogenesis brown adipose tissue can produce a multitude of autocrine, paracrine, and endocrine factors which might positively influence whole-body metabolism and function of other important organs. The effect of cold acclimation on brown adipose tissue is not however explored very well. The aim of this work was to asses selected parameters of respiration of isolated brown adipose tissue mitochondria of control rats living in 24 ± 1 řC and compare it with that of rats exposed to 8 ± 1 řC for 1 day, 3 days, 10 days, and 5 weeks. Results of this works were 1) the increase in respiration occurs after the 1-day cold exposure and 2) the highest respiration per 1 mg of mitochondrial protein appears to be after the 10 days of cold exposure. Key-words: Brown adipose tissue, mitochondria, respiration, cold acclimation
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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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The role of energy metabolism in cardioprotection induced by the adaptation to chronic hypoxia
Kolář, David ; Žurmanová, Jitka (advisor) ; Adamcová, Michaela (referee) ; Bardová, Kristina (referee)
Cardiac energy metabolism is the one of the most complex system in the body. To sustain life, but also to respond quickly to any sudden changes (e.g. running, emotional stress), the heart has developed a unique ability and has become a metabolic "omnivore". At physiological conditions, long chain fatty acids (LCFAs) present the major energetic source for the adult myocardium. However, the cardiac energy metabolism may be compromised during pathophysiological states. One of the most dangerous is, undoubtedly, ischaemia-reperfusion injury with its acute form, myocardial infarction. However, the adaptation to chronic hypoxia has been known for decades for its cardioprotective effect against I/R. Changes of cardiac energy metabolism induced by the adaptation have not been fully explored and the system conceals still too many secrets. This thesis has aimed to determine how adaptation to chronic hypoxia affects the cardiac metabolism of the rat LVs in the following set-ups: 1. The effect of chronic normobaric hypoxia (CNH; 3 weeks, 5500m) during a brief I/R protocol in vitro on the protein kinase B/hexokinase (Akt/HK) pathway, including the expression and phosphorylation of Akt, the expression and localization of HK, the expression of mitochondrial creatine kinase (mtCKS), and the level of Bcl-2 family...
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Analysis and identification of proteins in organ dysfunction using proteomic methods
Tůma, Zdeněk ; Matějovič, Martin (advisor) ; Lopot, František (referee) ; Hernychová, Lenka (referee)
Proteomics is the large-scale study of proteins, particularly their structures and functions. Proteomics has been utilized in medicine for investigation of disease mechanisms and biomarker discovery. Instrumental methods cover sample preparation, protein and peptide separation and mass spectrometry. At present, there is no proteomic method that can be used as universal for every sample. Analytical methods need to be adapted and optimized for certain samples. The aim of this work was to create methodic procedures and to interpret results of experimental and clinical research. The first part of the thesis includes experiments utilizing proteomics to study changes in the plasma proteome clinically relevant porcine model of sepsis-induced peritonitis. Proteomic analyzes were also starting methodological strategies in experiments aimed at kidney physiology and pathophysiology of acute kidney injury during sepsis. Renal biopsies were analyzed in order to study the time course of proteome changes caused by sepsis and surgery. The second part of the thesis contains experiments studying biocompatibility. A method for elution of proteins interacting with adsorbents used in extracorporeal liver support system and with hemodialyzer capillaries was prepared. Analysis of proteins adsorbed to polysulfone...
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The Role of Tyrosine Kinase Activity of Mitochondrial ERBB2/HER2 in Breast Cancer
Novotná, Eliška ; Rohlena, Jakub (advisor) ; Vrbacký, Marek (referee)
Breast cancer is a common malignant disease affecting millions of women worldwide. Amplification of HER2 oncogene, a tyrosine kinase receptor, in breast cancer allows application of targeted therapy, but approximately one third of patients develop resistance to treatment. Relocalization of HER2 from the plasma membrane into the mitochondria was found and suggested as one of the potential causes of such resistance. Here we document that the function of mitochondrial HER2 is distinct from that of HER2 in the plasma membrane. Mitochondrial HER2 enhances cancer cell energetic metabolism, proliferation and migration in vitro, and tumour formation in vivo in mice correlating with elevated level of ROS signalling. The kinase activity of mitochondrial HER2 is unaffected, therefore I investigated its role in mitochondrial HER2 function. Moderate, endogenous levels of the kinase activity of mitochondrial HER2 drive pro-tumorigenic properties of breast cancer cells, while constitutive kinase activity sensitizes these cells to cell death and attenuates tumour formation in animal models. On the other hand, impairment of kinase activity due to mutation in the ATP binding site of mitochondrial HER2 supports adherence-independent growth in vitro and tumor growth in vivo. We propose that HER2 function in...
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Activation and regulation of cell death in senescent cancer cells.
Holíček, Peter ; Anděra, Ladislav (advisor) ; Drbal, Karel (referee)
Cellular senescence is a distinct cell state, characteristic by cessation of cell proliferation and it is accompanied by specific morphological and biochemical alterations. Increasing and persisting incidence of senescence cells has been shown to have detrimental effect on an organism largely contributing to its ageing. Senescent cells also positively support tumour growth and can even stimulate carcinogenic transformation of surrounding cells. Moreover, senescence can be induced even in tumour cells spontaneously or by chemotherapy. Regardless of an initial stimuli and type of cells, there are two main senescence inducing pathways p16/pRb and p53/p21. Both senescent cells as well as senescent cancer cells seems to have modified apoptotic signalling at the level of mitochondria and Bcl-2 family proteins. In this study, we aimed to analyse effect of senescent state as well as pre-senescent (growth arrested state) induced by p16/pRb and p53/p21 signalling pathways on the response of H28 mesothelioma cancer cells-derived clonal cultures to various cell death-inducing stimuli. By inducible expression of p16 and p21 proteins in doxycycline-dependent manner, we forced cells to acquire senescent-like phenotype, which we detailly characterised. Our results showed that senescent-like phenotype, manifests...
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