|
|
Mitochondria as a target for anti-cancer therapy
Monschizadeh Tehrany, Shahin ; Truksa, Jaroslav (advisor) ; Kalous, Martin (referee)
Cancer is a complex disease that is characteristic by its heterogeneity in forms and symptoms. This diversity is caused by various mutations in oncogenes and tumor suppressor genes, which then makes cancer a very unclear and indistinct target. However numerous neoplastic characteristics are linked to the functions of mitochondria. This then makes mitochondria a center of interest of cancer research. Many cancer cells show the switch to the metabolism of aerobic glycolysis witch is characteristic by the increased glucose uptake, increased activity of biosynthetic pathways and lower oxidative capacity of mitochondria. Another mitochondria-linked modification is the increased production of reactive oxygen species in cancer cells, which are a source of new mutations and enhance cell proliferation. An increased transmembrane potential on the inner mitochondrial membrane is another very common feature that also promotes cell division and directly correlates with cancer malignancy. In this context a group of antitumor drugs called mitocans was discovered, that acts on the altered mitochondria of tumor cells. The activity of mitocans is ranging from the restoration of the function of pro-apoptotic molecules to the enforced cell death caused by oxidative damage done to the mitochondria of cancer cells....
|
|
|
Effect of biguanides on liver cells metabolism
Švecová, Eliška ; Kalous, Martin (advisor) ; Flachs, Pavel (referee) ; Hansíková, Hana (referee)
The extract from the plant Galega officinalis containing the guanidine derivative galegin has been used in the treatment of diabetes-associated complications since middle ages. Nevertheless, the positive effects of the treatment were often overweight by the adverse side effects. Some sixty years ago guanidin was replaced by the less toxic synthetic biguanide derivatives - metformin, phenphormin and buformin, the latter two being withdrawn due to the unacceptable risk of fatal lactate acidosis. Metformin is still widely used antidiabetics and belongs to the first choice drugs in the treatment of type 2 diabetes. Phenphormin is now gaining renewed attention with regard to its antineoplastic properties. Despite its long-term clinical use the mechanism of biguanides action is not fully understood yet. At present it is generally accepted that the core of its antihyperglycemic effect lays in the inhibition of hepatic gluconeogenesis. In contrast, there is less consensus regarding the particular metabolic pathway or target that are responsible for the metformin-induced attenuation of gluconeogenesis. For a long time, a hot candidate for metformin target in the cell was AMP-activated kinase (AMPK) but the metformin effect was proved also in mice carrying the dominant negative mutation of AMPK α subunit. Quite...
|
|
|
Regulation and Disorders of Mammalian Cytochrome c Oxidase
Kovářová, Nikola ; Houštěk, Josef (advisor) ; Stibůrek, Lukáš (referee) ; Kalous, Martin (referee)
Cytochrome c oxidase (COX) represents the terminal enzyme complex of respiratory chain metabolic pathway and it occurs as monomer, dimer or as a part of respiratory supercomplexes in the inner mitochondrial membrane. COX assembly process is complicated, highly regulated and depends on many ancillary proteins. Mutations in COX subunits, which are encoded by mitochondrial and nuclear DNA, or in genes encoding its assembly proteins are frequent cause of very severe mitochondrial disorders. SURF1 assembly protein participates in the first steps of COX assembly, but its exact function is not yet clarified. In humans, mutations of SURF1 gene lead to severe COX defect and fatal neurodegenerative disorder, Leigh syndrome. Knockout of SURF1 gene in mouse causes isolated COX defect as well, but less pronounced and without involvement of CNS. The aim of the thesis was detailed analysis of disturbed COX biogenesis in a condition of SURF1 gene mutations or SURF1 gene knockout, from assembly of COX monomer to interaction of COX into supercomplexes, and to the impact of isolated COX defect on other OXPHOS complexes. Mutations of SURF1 gene in patient's fibroblasts led to marked accumulation of COX assembly intermediates and to a defect in formation of functional COX monomer, which was preferentially built into an...
|
|
|
Role of membrane phospholipid remodeling, oxidative stress and PKC-δ upregulation in cardioprotection induced by chronic hypoxia
Ježková, Jana ; Kalous, Martin (referee)
Role of membrane phospholipid remodeling, oxidative stress and PKC- δ upregulation in cardioprotection induced by chronic hypoxia Introduction: Cardiovascular disease is the main cause of morbidity and mortality in industrially developed countries. Therefore, a number of experimental and clinical studies deal with the issue of how to increase tolerance to myocardial ischemia/reperfusion (I/R) injury. The present studies are concerned with mechanisms involved in the induction of endogenous cardioprotection after adaptation to intermittent altitude (IHA) hypoxia and influence of fat diets enriched with different fatty acids (FA) composition. We focused on changes in the composition of serum and heart lipids, the expression of PKC and on markers of oxidative stress and antioxidant enzyme activity in the myocardium. We also studied the role of reactive oxygen species (ROS) in the cardioprotective effect of IHA hypoxia using the antioxidant N-acetylcysteine (NAC). Methods: Adult male Wistar rats were exposed to IHA hypoxia in hyperbaric chamber, altitude 7000 m, 8 hours per day, 5 days a week, 25 exposures. Animals were fed by standard diet and diet enriched with 10% fat (saturated - SFA and MUFA mononemnasycené), 10% corn oil (n-6 polyunsaturated MK PUFA) and 10% fish oil (n-3 PUFA) in the diet experiment....
|
|
|
Role of nuclear-encoded subunits of cytochrome c oxidase
Čunátová, Kristýna ; Pecina, Petr (advisor) ; Kalous, Martin (referee)
Cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial electron transport chain and its main function is transfer of electrons to the terminal acceptor, oxygen. Moreover, COX contributes to the generation of proton gradient, which is indispensable for the production of vast majority of ATP molecules in the mammalian cells. The present work summarizes available data concerning the structure and function of nuclear-encoded subunits, which are specific for the eukaryotic form of COX. Particular emphasis is put on the role of subunit Cox4 and its regulatory properties within the enzyme. The study also describes other proteins associated with the enzyme, which are able to regulate the activity of COX, but are mainly involved in formation and stabilization of the respiratory supercomplexes. Based on the summarized data, three levels model of quaternary COX structure is postulated. They correspond to subunits of the catalytic center, nuclear-encoded subunits and substoichiometrically asociated proteins, which may give rise to several forms of COX with varying composition and differentially regulated function.
|
|
|
B-1 lymphocyte population and their role in the development of autoimmune diseases
Jabůrek, Filip ; Hájková, Michaela (advisor) ; Kalous, Martin (referee)
B-1 lymphocytes are specific type of B cells, development of witch occurs primarily in neonatal period of life. Later, the population is maintained through self-renewel. B-1 lymphocytes differ from classic folicular B lymphocytes in development from a distinct progenitor, expression of specific surface markers and production of polyreactive natural immunoglobulins. Since the discovery linking B-1 lymphocytes to the development of autoimmune diseases there was a shift in perspective on the B-1 lymphocytes and revaluation of the known facts. The aim of this thesis is to present a summary of current knowledge about B-1 lymphocytes, mechanisms of their effect on the development of autoimmune diseases and to outline the possible application of these findings in therapeutical practice. Key words: B-1 lymphocytes, autoimmune diseases, lupus, leukemia, SLE, B-CLL
|
|
|
Cytosolic hydrogenase in Trichomonas vaginalis
Dohnálková, Alena ; Hrdý, Ivan (advisor) ; Kalous, Martin (referee)
Trichomonas vaginalis is a flagellated microaerophilic protozoan from the group Excavata that cause trichomoniasis, the most common nonviral sexually transmitted disease in the world. This thesis deals with the study of hydrogenases, enzymes catalyzing reversible conversion of protons and electrons to molecular hydrogen. In T. vaginalis, hydrogenases have been identified so far only in hydrogenosomes, modified anaerobic mitochondia that are involved in energy metabolism. We proved the presence of this enzyme also in the cytosol of T. vaginalis. Among several hydrogenase paralogues present in the genome, we selected an appropriate gene for the putative cytosolic hydrogenase (C-Hyd) and verified its cytosolic localization in the cells with overexpressed C-Hyd protein. Based on the determination of hydrogenase activities in different cell compartments and fractions obtained by affinity chromatography, we demonstrated the hydrogenase activity of C-Hyd protein, which means that C-Hyd is a functional hydrogenase. Identification of hydrogenase in T. vaginalis cytosol changes our understanding of trichomonad core metabolism and opens the door for the research of unexplored metabolic capabilities of this parasite.
|
|
|
Evolution of life - the RNA world
Čvirik, Rastislav ; Markoš, Anton (advisor) ; Kalous, Martin (referee)
Origin and evolution of life represents complex and not yet resolved question in a field of natural sciences. One of the possible explanation is held by "The RNA world theory". In its general notion, RNA molecule can function both as genetic carrier and catalyst. Further it assumes, that in early development of life, genetic continuity was assured by the replication of RNA whereas proteins and DNA only appeared later. In a light of recent reasearch there is now a strong evidence supporting existence of this world. However, there are still several problems associated with prebiotic chemistry reactions and number of unresolved paradoxes. Although this teory does not directly explain life's origins, it offers us an alternative how such event may occured on primitive Earth. Powered by TCPDF (www.tcpdf.org)
|
|
|
New components and functions of mitochondrial ATP synthase.
Ho, Dieu Hien ; Pecina, Petr (advisor) ; Kalous, Martin (referee)
The system of oxidative phosphorylation, or respiratory chain in mitochondria gives the eukaryotic cell total majority of the energy it receives and uses in the form of ATP. F1Fo-ATP synthase, powered by the proton-motive force is directly responsible for the ATP synthesis. Diseases connected to the ATP synthesis can have even lethal consequences. There is therefore no doubt about the need for a detailed analysis of the structure of this enzyme. What is left is to reveal the structure of the transmembrane domains, which are not involved in the synthesis itself, but they can for example work as stabilisers or assembly factors. Outside the synthesis activity the dimers of F1Fo-ATP synthase are apparently taking part in the formation of the cristae of the inner membrane of a mitochondrion. Recently, the role of the enzyme is also considered in the creation of the mitochondrial permeability transition pore.
|
|
|
Alternative 2-keto acid oxidoreductases (KOR) in Trichomonas vaginalis: Artifact of histochemical staining
Zedníková, Věra ; Kalous, Martin (referee)
In 1999, Brown et al reported that Trichomonas vaginalis possesses two new enzymes of carbohydrate metabolism, alternative 2-keto acid oxidoreductases (KOR). These enzymes preferentially used indolepyruvate in a reaction that resembled that of pyruvate:ferredoxin oxidoreductase (PFO). However, the KOR did not use ferredoxin as electron acceptor and remained active in metronidazole-resistant trichomonads lacking PFO. Therefore, it was proposed that the KORs may help trichomonads to survive in the presence of metronidazole. In the study from 2012, we showed that the apparent KOR activity was caused by the non-enzymatic reduction of the indicator dye, nitroblue tetrazolium (NBT), by indolepyruvate, which is facilitated by Triton X-100 used to prepare the membrane fractions. The low level indolepyruvate-dependent activity that is present in T. vaginalis strains sensitive to metronidazole is catalyzed by PFO, which was verified using the pure enzyme. Presumed activity of alternative 2-keto acid oxidoreductases was caused by an experimental artifact and these enzymes do not exist in T. vaginalis.
|
guest ::
RSS feed.