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The role of extracellular vesicles in transmission of dsRNA viruses in parasitic protist Trichomomas vaginalis.
Horáčková, Jana ; Rada, Petr (advisor) ; Voleman, Luboš (referee)
Trichomonas vaginalis is a parasitic protist found in the human urogenital tract, where it adheres to the epithelial cells. During infection, T. vaginalis cells release extracellular vesicles that allow them to communicate with each other and modulate the host immune response. Most studied T. vaginalis strains contain dsRNA Trichomonasviruses (TVVs). These viruses belong to the Totiviridae family, which includes other dsRNA viruses from various parasitic protists. TVV is transmitted vertically to the daughter cells during cell division. Horizontal transfer of TVV between T. vaginalis cells has not yet been proven. TVV particles were found inside small extracellular vesicles that release infected T. vaginalis into the extracellular space. In this thesis, it was shown that TVV could be transmitted between trichomonads during co-cultivation of infected and uninfected trichomonads. However, stable TVV infection of trichomonads was not observed. It was also proven that extracellular vesicles from infected trichomonads could transmit TVV among other trichomonads. Nevertheless, this way of transmission did not lead to the stable TVV infection of trichomonads either.
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Role of a SNARE protein in the biogenesis of Giardia intestinalis mitosomes.
Voleman, Luboš ; Doležal, Pavel (advisor) ; Nohýnková, Eva (referee)
SNARE proteins play essential role in most membrane fusions taking place in eukaryotic cell. They are responsible for all fusions that occur across endocytic and secretory pathways. Apart from these processes stand mitochondria and plastids. Fusion of these organelles is directed by specific protein machineries. In this work we review up-to-date information on SNARE mediated membrane fusion and fusion of outer and inner mitochondrial membranes with an emphasis on situation in flagellated protozoan parasite Giradia intestinalis. It was suggested that one of typical SNARE protein in Giardia (GiSec20) is localised to its highly reduced mitochondria called mitosomes. This protein is also essential for surviving of Giardia trophozoites. In this work we show that mitosomal localization of Gisec20 is caused by episomal expression however the protein is localised to endoplasmic reticulum under physiological conditions. Using GFP tag we were able to characterize its targeting signal which showed to be localised in transmembrane domain of GiSec20. This signal targets the protein to mitosomes of G. intestinalis and S. cerevisiae, respectively. Mitosomal localization was prevented by adding 3'UTR to gene sequence and its episomal expression. This suggests existence of targeting mechanism based on information...
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Interactions of Mitochondria with Other Cellular Structures
Vinopalová, Martina ; Doležal, Pavel (advisor) ; Voleman, Luboš (referee)
In cells, mitochondria fulfil diverse set of roles, including a production of energy-rich molecules, which are necessary for proper functioning of the cell, calcium homeostasis, apoptosis and even biosynthesis of Fe-S centres, heme and steroids. To coordinate some of these processes with events occurring in the rest of the cell, mitochondria need to communicate with the other cellular structures through their physical contacts. Resulting intracellular platforms give rise to additional mitochondrial functions. This thesis summarizes current findings from the cells of mammalian model organisms and the budding yeast Saccharomyces cerevisiae about the interactions of this semiautonomous organelle with other cellular components and about the functions, which these interactions mediate.
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Biogenesis of Giardia intestinalis mitosomes
Voleman, Luboš ; Doležal, Pavel (advisor) ; Faso, Carmen (referee) ; Dawson, Scott C. (referee)
7 ABSTRACT Mitochondria of opisthokonts undergo permanent fusion and fission throughout the cell cycle. Keeping these two processes in balance is vital for various aspects of mitochondrial and cellular homeostasis. Both mitochondrial fusion and division mechanisms are controlled by highly conserved dynamin-related GTPases that are present in all kingdoms of life. The aspects of mitochondrial dynamics outside the opisthokonts is, however, almost completely unexplored phenomenon. In our work, we introduced a tool for live imaging of the reduced forms of mitochondria into model organisms Giardia intestinalis and Trichomonas vaginalis, anaerobic protist parasites from the Excavata supergroup of Eukaryotes. Using this technique, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, of G. intestinalis. The division of mitosomes is restricted to Giardia mitosis and is absolutely synchronized with the process. The synchrony of the nuclear and the mitosomal division persists also during the encystation of the parasite. Surprisingly, the sole dynamin-related protein of the parasite seems not to be involved in mitosomal division. However, throughout the cell cycle mitosomes associate with the...
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Iron homeostasis in malaria
Wernerová, Klára ; Šuťák, Róbert (advisor) ; Voleman, Luboš (referee)
Although malaria is a well-studied infectious disease, we are still unable to fight it effectively, as evidenced by a large number of infected people. Many drugs are available against malaria. However, because of incessantly emerging resistances, new, more effective antimalarials need to be developed. One possibility is to target the parasite's iron metabolism, the essential element of all organisms. Iron participates in DNA synthesis, respiration, energy production. It acts as a cofactor of ribonucleotide reductase, and metalloproteins with FeS clusters or heme. During the infection, the parasite must compete with the host for nutrients, including iron. The mechanism of iron uptake or excretion in malaria parasite is not completely clear. Only two iron transporters are known, but it is already evident, that there must be more of them. The Plasmodium parasite digests a large amount of hemoglobin, which is degraded into free heme and denatured globin. Free heme is toxic to the cell though. Plasmodium defends itself from the toxicity of free heme by forming chemically inert hemozoin. This unique mechanism of protection against the free heme toxicity is very useful for Plasmodium and other blood parasites, but it also becomes an advantageous target for drugs because the mechanism is present only in...
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The role of dynamin in human pathologies
Zavadilová, Kristýna ; Macůrková, Marie (advisor) ; Voleman, Luboš (referee)
Dynamin (DNM) belongs to the family of large GTPases, which are characterized by their ability to hydrolyse GTP. Although DNM participates in many cell processes such as synaptic recycling, Golgi transport or regulation of cytoskeletal dynamics, its most imporant function is membrane scission during vesicle budding from the plasma during clathrin-mediated endocytosis. Human DNM is encoded by three different genes. DNM1 and DNM3 are most expressed in the nervous system, particularly in the brain, whereas DNM2 is expressed ubiquitously. Mutations in this gene cause two congenital neuromuscular diseases. One of them is autosomal dominant type of Centronuclear myopathy, manifested by skeletal muscle atrophy, the other is dominant intermediate type of Charcot-Marie-Tooth neuropathy, which affects myelination and neurotransmission in the peripheral nervous system. Myopathy mutations may increase GTPase activity and higher DNM2 oligomerization, while neuropathy mutations may cause decreased GTPase activity and loss of phospholipid binding properties of DNM2. Despite these findings, the mechanism by which DNM2 cause these two diseases is still unknown. By understanding the function of DNM in cell processes can help in outlining therapeutic approaches for the aforementioned diseases.
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Biogenesis of Giardia intestinalis mitosomes
Voleman, Luboš ; Doležal, Pavel (advisor) ; Faso, Carmen (referee) ; Dawson, Scott C. (referee)
7 ABSTRACT Mitochondria of opisthokonts undergo permanent fusion and fission throughout the cell cycle. Keeping these two processes in balance is vital for various aspects of mitochondrial and cellular homeostasis. Both mitochondrial fusion and division mechanisms are controlled by highly conserved dynamin-related GTPases that are present in all kingdoms of life. The aspects of mitochondrial dynamics outside the opisthokonts is, however, almost completely unexplored phenomenon. In our work, we introduced a tool for live imaging of the reduced forms of mitochondria into model organisms Giardia intestinalis and Trichomonas vaginalis, anaerobic protist parasites from the Excavata supergroup of Eukaryotes. Using this technique, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, of G. intestinalis. The division of mitosomes is restricted to Giardia mitosis and is absolutely synchronized with the process. The synchrony of the nuclear and the mitosomal division persists also during the encystation of the parasite. Surprisingly, the sole dynamin-related protein of the parasite seems not to be involved in mitosomal division. However, throughout the cell cycle mitosomes associate with the...
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Interactions of Mitochondria with Other Cellular Structures
Vinopalová, Martina ; Doležal, Pavel (advisor) ; Voleman, Luboš (referee)
In cells, mitochondria fulfil diverse set of roles, including a production of energy-rich molecules, which are necessary for proper functioning of the cell, calcium homeostasis, apoptosis and even biosynthesis of Fe-S centres, heme and steroids. To coordinate some of these processes with events occurring in the rest of the cell, mitochondria need to communicate with the other cellular structures through their physical contacts. Resulting intracellular platforms give rise to additional mitochondrial functions. This thesis summarizes current findings from the cells of mammalian model organisms and the budding yeast Saccharomyces cerevisiae about the interactions of this semiautonomous organelle with other cellular components and about the functions, which these interactions mediate.
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Role of a SNARE protein in the biogenesis of Giardia intestinalis mitosomes.
Voleman, Luboš ; Doležal, Pavel (advisor) ; Nohýnková, Eva (referee)
SNARE proteins play essential role in most membrane fusions taking place in eukaryotic cell. They are responsible for all fusions that occur across endocytic and secretory pathways. Apart from these processes stand mitochondria and plastids. Fusion of these organelles is directed by specific protein machineries. In this work we review up-to-date information on SNARE mediated membrane fusion and fusion of outer and inner mitochondrial membranes with an emphasis on situation in flagellated protozoan parasite Giradia intestinalis. It was suggested that one of typical SNARE protein in Giardia (GiSec20) is localised to its highly reduced mitochondria called mitosomes. This protein is also essential for surviving of Giardia trophozoites. In this work we show that mitosomal localization of Gisec20 is caused by episomal expression however the protein is localised to endoplasmic reticulum under physiological conditions. Using GFP tag we were able to characterize its targeting signal which showed to be localised in transmembrane domain of GiSec20. This signal targets the protein to mitosomes of G. intestinalis and S. cerevisiae, respectively. Mitosomal localization was prevented by adding 3'UTR to gene sequence and its episomal expression. This suggests existence of targeting mechanism based on information...
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