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Cell polarity establishment and changes during Saccharomyces cerevisiae cell cycle
Luxová, Pavla ; Malcová, Ivana (advisor) ; Šťovíček, Vratislav (referee)
Cell polarity can be defined as an asymmetric organization and distribution of biomolecules, cellular organelles and structures which are important for many cellular processes. Cell polarity establishment is essential for the proper development of all organisms. This work focuses on main mechanisms of cell polarity establishment, its maintenance and changes during Saccharomyces cerevisiae cell cycle. Budding yeast is one of the preferred model organism. Bud site selection is determined by the spatial landmarks which are accumulated at the previous division site. The spatial landmarks are recognized by Rho GTPases which act on their effectors and thus affect the actin cytoskeleton and septins. These structures are essential for polarized bud growth that is coordinated with the cell cycle. Newborn cells arising after the bud separation from the mother cell at the end of each cycle are able to undergo many more division cycles than their mothers what is a new challenge to study cell polarity in terms of cell aging.
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Study of the mammalian oncogenic transcription factors in the yeast model
Novák, Josef ; Zámostná, Blanka (advisor) ; Šťovíček, Vratislav (referee)
Yeast serves as a useful tool for studying cellular processes and therefore a large amount of techniques and protocols has been developed. There are special methods for studying the transcriptional factors in yeast, such as modified yeast two-hybrid screens, yeast one-hybrid screens and systems studying ability of transcription factors to transactivate a reporter gene. Oncogenes from AP-1 complex, Myc and Myb protein families are described in this work. Using a yeast model the structural-functional properties of proteins can be easily studied and in some cases even their ability of oncogenic transformation can be predicted (FASAY or ability of c-Myc to transactivate a reporter gene). However, results from yeast models must be confirmed in mammalian cells. 1
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Viruses and cytosketelon of the cell nucleus
Cibulka, Jakub ; Forstová, Jitka (advisor) ; Šťovíček, Vratislav (referee)
The nuclear cytoskeleton (the nucleoskeleton) provides a structural integrity to the nucleus and is involved in number of key processes including transcription, chromatin remodelling and mRNA transport. The nucleoskeleton consists of nuclear lamins, nuclear actin and other proteins. Some viruses, which replicate themselves in the nucleus, use nuclear cytoskeleton in their life-cycle. On the other hand the nucleosketon may also represent a barrier for viral infection. Herpesviruses need nuclear actin for capsid assembly and transport, but they have to desintegrate the nuclear lamina in order to escape the nucleus. Nuclear actin also participates in the morphogenesis and probably nuclear export of baculovirus capsids. Some retroviruses transport their unspliced RNAs from the nucleus using nuclear actin and there is also some evidence of retrovirus-induced nuclear lamina disruption. In this work, I focus on the interactions of above-mentioned viruses with the nuclear cytoskeleton (namely nuclear actin and lamins).
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Vlastnosti DNA vazebných mutant proteinů CSL
Teska, Mikoláš ; Folk, Petr (advisor) ; Šťovíček, Vratislav (referee)
Notch pathway plays a critical role during the development and life of metazoan organisms. CSL proteins are the component of the Notch pathway that mediates the regulation of target genes. The discovery of CSL-like proteins in yeast raised the question of their function in unicellular organisms which did not utilize the canonical Notch pathway. CSL-homologues in yeast are conserved in parts that are important for DNA binding and for fission yeast proteins it was shown that they bind to CSL recognition elements in vitro. In fission yeast, CSL paralogues Cbf11 and Cbf12 play antagonistic roles in cell adhesion and the coordination of cell and nuclear division. Yeast CSL proteins have long and intrinsically unstructured N- terminal domains compared to metazoan CSL proteins. In this study, we investigated the functional significance of these extended N-termini of CSL proteins by their complete removal. For newly constructed truncated variants of proteins Cbf11 and Cbf12 in Schizosaccharomyces pombe we observed the lack of ability to bind CSL recognition RBP probe. The removal of N-terminal parts of CSL proteins in fission yeast led to the change in their cellular localization. Once strongly preferred nuclear localization changed by the removal of N-terminal domains to cytoplasmic localization with a...
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Polymer systems for siRNA delivery
Blažková, Jana ; Pechar, Michal (advisor) ; Šťovíček, Vratislav (referee)
The process of RNA interference (RNAi) is a natural phenomenon posttranscriptionally controlling gene expression by means of small double-stranded RNA molecules (dsRNA). Small interfering RNA (siRNA) is a small dsRNA that can be used for targeted gene silencing as an alternative therapeutic treatment of genetic diseases. For in vivo administration, siRNA must be protected against degradation to ensure its efficient delivery to target cells using sophisticated vectors. This work is focused on description of non-viral vectors based on cationic polymers, forming polyelectrolyte complexes with siRNA (polyplexes), and surface-modifying hydrophilic polymers enabling protection of the vector during its transport in the bloodstream.
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Molecular mechanism of formation and development of colonies of wild Saccharomyces cerevisiae strains
Šťovíček, Vratislav
Yeasts are capable of forming a wide range of multicellular communities, which enable the survival in harmful and changing environment. Surface associated biofilms, often connected with infections in human body, and colonies can serve as an example of such populations. This work investigates formation and development of complex structured colonies of Saccharomyces cerevisiae, which can be considered as a distinctive feature of yeast strains isolated from the wild. Architecture and properties of such colonies are fundamentally different from the spatially undifferentiated colonies of most of laboratory strains and resemble in many ways rather natural biofilms of pathogenic yeasts. Yeast populations use specific developmental processes induced by communication mechanisms to synchronize the early stages of their development. Formation of specific three-dimensional colony architecture is enabled by the presence of extracellular matrix and adhesive protein Flo11p which provide stability and integrity of the whole structure. Protection of the colonies is accomplished by spatially differentiated cell subpopulations using various mechanisms such as expression of efflux pumps capable of removing toxic substances or production of extracellular matrix functioning also as selectively permeable barrier. Phenotypic...
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