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Study of human NADH:ubiquinone oxidoreductase deficiency
Rodinová, Marie ; Hansíková, Hana (advisor) ; Kalous, Martin (referee)
NADH: ubiquinone oxidoreductase (complex I) is the most complicated enzyme of mitochondrial oxidative phosphorylation system (OXPHOS). Complex I is localised in the inner mitochondrial membrane and is composed of 45 subunits. Seven of them are coded by mtDNA, thirty eight subunits are coded by nDNA. Function of complex I is NADH oxidation and creation of proton gradient in intermembrane space by proton translocation. Mitochondrial disease caused by complex I defect are the most frequent OXPHOS disorders. Large-scale symptoms mostly affect organs with high energy demand like brain, muscle or heart. The aim of study was to characterize the impact of isolated complex I deficiency on cellular, enzymatic and protein level in patient-derived skin fibroblasts with m.3697G>A mutation in MTDN1 and c.[229C>T];[476C>A] mutations in NDUFS8. Both mutated subunits are parts of catalytic core of complex I. Heteroplasmy of mtDNA mutation m.3697G>A in fibroblast cells reached more than 90 %. Mitochondrial ultrastructure was disrupted in both patients compared to control. Mitochondrial network was nonhomogenous, mitochondrial ultrastructure showeed low cristae level and content of reactive oxygen species in both patients was significantly increased in comparison with control. Catalytic activity and protein level of...
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Study of the composition and organization of cytochrome P450 system by covalent crosslinking
Koberová, Monika ; Hodek, Petr (advisor) ; Hansíková, Hana (referee)
The system of mixed function oxygenase (MFO system) participates in significant roles in the metabolism of endogenous compounds and xenobiotics. This system contains cytochrome P450, NADPH:cytochrome P450 reductase, and also there are assigned NADH: cytochrome b5 reductase and cytochrome b5. It was proved that cytochrome b5 can stimulate or inhibit cytochrome P450 (CYP)-dependent reactions and even change the ratio of resulting metabolites. The mechanism of cytochrome b5 action has not been fully elucidated yet. Elucidation of protein-protein interactions in MFO system and determination of topology of this system could explain the mechanism of cyt b5 action. The covalent cross- linking technique is suitable method for identifying protein-protein interactions within the membrane. Cytochrome b5 contains 3 methionines and in 2 cases the methionines are localized in a short hydrophobic C-terminal membrane anchor. Interactions with cytochrome P450 in the membrane environment can be identified by substitution of two methionine for photoactivatable analogue of methionine (photo-methionine) and subsequent photoactivation. This work is focused on expression and isolation of photo-cytochrome b5 (photo- cyt b5), cytochrome b5 analogue with incorporated photo-methionine. Conditions for photo-methionine...
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Fumarate hydratase as tumor suppressor
Kedrová, Kateřina ; Hansíková, Hana (advisor) ; Befekadu, Asfaw (referee)
1 Abstract Fumarate hydratase (fumarase, EC 4.2.1.2) catalyzes the reverse hydration of fumarate to S malate. In mammalian cells, it changes fumarate in the mitochondrial matrix as a part of the citric acid cycle and in the cytosol, where functions to metabolize fumarate the product of the degradation of some amino acids, of ammonia transformation to urea acid or of the purine nucleotide synthesis. . In human cells, fumarase is encoded by FH gene localized on chromosome 1 (1q42.1). The FH gene consists of 10 exons and encodes for a 510 amino acids-long protein including the N-terminal mitochondrial signal sequence. Germline heterozygous FH mutations were found in two autosomal dominant syndromes. These are multiple cutaneous and uterine leiomyomatosis (MCUL1 or MCL) and hereditary leiomyomatosis and renal cell cancer (HLRCC). In the most of tumors from these patients, loss of FH gene heterozygosity was also found. It has been suggested that fumarase acts as a tumor suppressor according to Knudson's two-hit hypothesis. The aim of the bachelor thesis was to study the activity and amounts of fumarase in a series of 22 samples of uterine leiomyomas from 22 young women patients (21-31 years) with sporadic uterine leiomyomas. As a control sample, uterine leiomyoma from a 38-year-old patient was used. Activity of...
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Role of chemopreventive compounds and food additives in the process of metabolism and activation of carcinogens by cytochromes P450
Fousová, Petra ; Hodek, Petr (advisor) ; Hansíková, Hana (referee)
The origin of malignant tumors have different internal and external factors and also have been shown that, for majority of exogenous chemical carcinogens, the genotoxicity depends on metabolic activation through enzymes. Members of the subfamilies CYP1A are involved in activation of precarcinogens, for example the heterocyclic amine PhIP. One of the main approaches to achieve a reduction in a cancer risk is prevention. Recently, the consumption of dietary supplements containing various chemopreventive substances, such as flavonoids, has expanded. On the other hand, some negative effects of these compounds were also confirmed, especially their ability to induce cytochrome P450 and thus increase the risk of activating precarcinogens. In this study, the inductive effect of a single administration of chemopreventive compounds, namely the effect of -naphtoflavon to cytochrome P450, had been investigated. Furthermore, a sequential study was carried out. In this study rats were first given an inducer, the -naphtoflavon, and after a passed interval they were given the carcinogen PhIP. Finally, the effect of PhIP on the activity of cytochrome P450 has been studied in vitro. KEY WORDS: cytochrome P450, carcinogens, chemopreventive compounds
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Complex I of mitochondrial respiratory chain a its disorders.
Rodinová, Marie ; Kalous, Martin (referee) ; Hansíková, Hana (advisor)
NADH: ubiquinone oxidoreductase (Complex I) is a multisubunit protein complex of inner mitochondrial membrane. Complex I is the biggest and most complicated part of oxidative phosphorylation system, which is responsible for the cell ATP production. It consists of 45 subunits. 7 subunits are mitochondrial encoded, remainder 38 are nuclear encoded. NADH: ubiquinone oxidoreductase has L-shaped structure, which is built of two arms: membrane arm and matrix located peripheral arm. Complex I oxidize the NADH molecule. The electron transport is coupled with proton pumping across the inner mitochondrial membrane to intermembrane space, where proton gradient developed and which is used by ATP synthase to ATP synthesis. Deficiencies of NADH: ubiquinone oxidoreductase represent extensive, clinically and genetic heterogeneous group of mitochondrial diseases. Decrease of activity and amount of complex I, decrease of ATP production, changes of membrane potential, mitochondrial morphology and mitochondrial network and increasing of production of reactive oxygen species are found in cells with defects of NADH: ubiquinone oxidoreductase. Combination of this features lead to serious illnesses, which are almost fatal and we still haven't any useful therapy. Aim of this study is to summarize present knowledge about...
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Study of mitochondrial ultrastructure and functions in selected mitochondrial and lysosomal storage disorders
Kostková, Olga ; Hansíková, Hana (advisor) ; Šmíd, František (referee) ; Hyánek, Josef (referee)
This thesis has been worked out in The laboratory for study of mitochondrial disorders (Departement of Pediatrics, 1st Faculty of Medcine, Chales university in Prague) and in cooperation with The Institute of Inherited Metabolic Disorders. Mitochondrial disorders represent a heterogeneous group of diseases with the onset at any age from neonatal period till adulthood, mostly presented with very severe clinical courses of disease. The mammalian organism is fully dependent on mitochondrial oxidative phosphorylation system as on the major energy producer of the cell. Therefore the mitochondrial disorders affect mainly high energy demanded tissues such as brain, heart or muscle. Simillar phenotype is observed in many lysosomal storage disorders. Despite of expanding knowledge of molecular basis of mitochondrial and lysosomal disorders, it may be still difficult to explain the exact pathogenesis of disease as well as the prognosis for patients and their families. Mitochondrial functions affect more than just energy production; they contribute in initiation of apoptosis, in cellular calcium homeostasis, and in production of reactive oxygene species. Disturbed mitochondria become a goal of autophagy mediated by the lysosomal compartement. The results of our study enable: 1. better understanding of the tissue...
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The study of activation and detoxication metabolism of the anticancer drug ellipticine by the cytochrome P450 system in vitro and in vivo…
Kotrbová, Věra ; Stiborová, Marie (advisor) ; Hansíková, Hana (referee) ; Souček, Pavel (referee)
Gen. Physiol. Biophys. (2006), 25, 245-261 245 Oxidation Pattern of the Anticancer Drug Ellipticine by Hepatic Microsomes - Similarity Between Human and Rat Systems M. Stiborová1 , L. Bořek-Dohalská1 , D. Aimová1 , V. Kotrbová1 , K. Kukačková1 , K. Janouchová1 , M. Rupertová1 , H. Ryšlavá1 , J. Hudeček1 and E. Frei2 1 Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic 2 Division of Molecular Toxicology, German Cancer Research Center, Heidelberg, Germany Abstract. Ellipticine is an antineoplastic agent, whose mode of action is based mainly on DNA intercalation, inhibition of topoisomerase II and formation of DNA adducts mediated by cytochrome P450 (CYP). We investigated the ability of CYP enzymes in rat, rabbit and human hepatic microsomes to oxidize ellip- ticine and evaluated suitable animal models mimicking its oxidation in humans. Ellipticine is oxidized by microsomes of all species to 7-hydroxy-, 9-hydroxy-, 12- hydroxy-, 13-hydroxyellipticine and ellipticine N2 -oxide. However, only rat micro- somes generated the pattern of ellipticine metabolites reproducing that formed by human microsomes. While rabbit microsomes favored the production of ellipticine N2 -oxide, human and rat microsomes predominantly formed 13-hydroxyellipticine. The species difference in...
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