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Localization matters: function of paxillin and phopholipids in the cell nucleus
Marášek, Pavel ; Hozák, Pavel (advisor) ; Půta, František (referee) ; Žárský, Viktor (referee)
(English) Both paxillin and PIP2 are well known components of the cell, although of a distinct origin. Focal adhesion protein paxillin spreads the signals from extracellular matrix via integrins and growth factor receptors to affect cellular motility and migration (Schaller, 2001). PIP2, a major structural component of cytoplasmic membrane, is utilized by phospholipase C to generate second messenger molecules (Hokin and Hokin 1953; Streb et al. 1983). Both molecules were recently shown to be localized in the nucleus. Their original functions have been well established, but together with other research colleagues we are now shedding more light on completely different functions of these biological molecules and moreover, in the different compartments than they were primarily believed to function in. Here, we introduce paxillin as an important factor of the cell nucleus, where it regulates transcription of two important growth-related genes, IGF2 and H19. It does not affect the allelic expression of these imprinted genes, it rather regulates long-range chromosomal interactions between H19 or IGF2 promoter, and the shared distal enhacer on an active allele. In detail, paxillin stimulates the interaction between the enhancer and the IGF2 promoter, activating IGF2 gene transcription, while it restrains...
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GAL4/UAS binary system as a toll for the study of gene function
Soukup, Tomáš ; Krylov, Vladimír (advisor) ; Půta, František (referee)
GAL4/UAS system is a bipartite gene engineering tool, enabling ectopic expression in temporal and tissue-specific manner in vivo. Design of this technique is based on a mechanism of gene transcription, which was elucidated of large portion by an experimental study of Saccharomyces cerevisiae regulation of metabolic control circuit for processing galactose. It is possible to generate hundreds of stable transgenic lines by independent incorporation of the gene for the transcription factor Gal4p and its binding sequence (UAS), respectively, by using transposible or specific-sequence integration techniques. An individual organism, manifesting ectopic expression in suitable, adjustable conditions, can be obtained by cross breeding individual of GAL4 lines with individual from UAS line. This thesis represents a synthesis of the basic principles of GAL4/UAS system and its variants, particularly adapted to the needs of genetic manipulation of model organisms Drosophila melanogaster and Danio rerio. Additionally, this text summarizes the connection GAL4/UAS system with other techniques and briefly highlights the potential for practical applications mainly in research area of neurology. Powered by TCPDF (www.tcpdf.org)
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The function of Slu7 protein in Saccharomyces cerevisiae pre-mRNA splicing
Ničová, Eva ; Půta, František (advisor) ; Vašicová, Pavla (referee)
Alternative splicing is one of the mechanisms how to regulate gene expression. Under different conditions, different mRNAs encoding proteins with different function, localization or stability can be made from one cellular transcript. The human hSlu7 protein affects the alternative splicing of some genes through alternative 3'splice site (3'SS) selection. Although it was thought that alternative splicing is absent from Saccharomyces cerevisiae, recent results argue against such conclusion. We therefore decided to characterize the function of the yeast Slu7 protein, which participates in the second step of splicing and is closely associated with the 3'SS selection. We focused on a highly conserved uncharacterized motif in the essential part of the Slu7 protein named the RED motif. Mutations in this motif caused second step splicing defects with some substrates and altered the alternative 3'SS usage ratio of some splicing constructs. Our results implicate a role for the RED motif in selecting proper 3'splice sites, especially the distal ones. Genetic interactions of slu7 mutations with PRP22 and PRP45 mutant alelles add to the intricate interaction network of splicing factors and suggest a possible role of Slu7p in facilitating the Prp22p association with the spliceosome.
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Alakali-metal-cation homeostasis in pathogenic Candida species
Elicharová, Hana ; Sychrová, Hana (advisor) ; Heidingsfeld, Olga (referee) ; Půta, František (referee)
Several tens of Candida species belong to the opportunistic human pathogens capable of inducing life-threatening infections in immunocompromised patients. Virulence of single Candida species depends among others on their resistance to the variable external conditions. The maintenance of alkali-metal-cation homeostasis, which means the ability to accumulate sufficient amount of potassium cations and on the other hand to survive under high extracellular concentrations of alkali-metal cations, is essential for growth and virulence of Candida cells. We observed the negative effect of fluconazole (FLC) on salt-tolerance of six Candida species and found that it is independent of the species level of FLC- resistance. FLC hyperpolarizes plasma membrane of Candida cells and therefore increases non-specific uptake of alkali-metal cations which results in strongly increased salt-sensitivity of Candida cells. The FLC-induced hyperpolarization also results in an increased sensitivity of Candida cells to the antifungals which are positively charged and are driven into the cells by the membrane potential. The effect of fluconazole on membrane potential and thus on the uptake of alkali- metal cations into the cell turned our attention to the homeostasis of potassium cations whose high intracellular concentration is...
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Regulation of S. cerevisiae TUB1 and TUB3 paralogous genes expression by Prp45
Cihlářová, Zuzana ; Půta, František (advisor) ; Schierová, Michaela (referee)
Prp45 is an essential splicing factor of budding yeast Saccharomyces cerevisiae. The human ortholog of Prp45 - protein SNW1/SKIP - is involved in splicing and probably influences transcription and histone modification. The genetic interacion of Prp45 with splicing factors is well described. We have additionally demonstrated that Prp45 genetically interacts also with factors involved in transcription regulation and histone modification enzymes. Our preliminary data therefore suggest that Prp45 might be a factor that connects processes of splicing, transcription, and chromatine modification and dynamics in S. cerevisiae. The first aim of this project was to investigate the role of introns in intra- and intergenic expression regulation of paralogous genes TUB1 and TUB3 and whether is this regulation influenced by aberrant splicing. Using quantitative PCR we found that expression of paralogous genes TUB1 and TUB3 is not dependent on the presence of their introns or correct splicing. The second aim of this project was to explore the potential role of Prp45 in the regulation of chromatin state. For this purpose, we used the system of β-estradiol-induced expression of myc-tagged histon H3 and determined its incorporation into nucleosomes by chromatin immunoprecipitation. Despite the lack of...
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Cysteine tRNA regulates protein synthesis in human cell lines
Kučerová, Michaela ; Beznosková, Petra (advisor) ; Půta, František (referee)
A significant number of known human genetic diseases is associated with nonsense mutations leading to the introduction of a premature termination codon into the coding sequence. A termination codon can be read through by its near-cognate tRNA (tRNA with two anticodon nucleotides base-pairing with a stop codon); potentially generating C-terminally extended protein variants. In yeast, UGA stop codon was described to be read through by tRNA-Trp and tRNA-Cys. Similar was observed for tRNA-Trp in human HEK293T cell line. The aim of this thesis was to investigate if human tRNA-Cys can act as a near-cognate tRNA in human HEK293T cell line. There are two isoacceptors which constitute the tRNA-Cys family, with ACA and GCA anticodon. There are 1 and 23 isodecoders to the ACA and GCA anticodons, respectively. Here, altogether as many as nine tRNA-Cys isodecoders (distinct in their sequence and with varying levels of expression) were tested for their ability to increase UGA readthrough in HEK293T using p2luci and pSGDluc dual-luciferase reporter vectors. In both p2luci and pSGDluc, we observed that at least one tRNA-Cys isodecoder, tRNA-Cys-GCA-4-1, is capable of significantly elevating the UGA readthrough levels when overexpressed in HEK293T. This indicates that similarly to yeast, tRNA-Cys is capable of...
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Watersoluble polymer nanomaterials tailored for anti-tumor therapy
Vinklerová, Laura ; Etrych, Tomáš (advisor) ; Půta, František (referee)
Anti-tumor treatment involves several therapeutic approaches. One of them is chemotherapy with low-molecular-weight cytostatic drugs, whose disadvantage is the systemic manifestation of cytostatic effects even in healthy tissue. Nevertheless, at the end of the last century, a new concept of high molecular weight polymer nanomaterials with minimized the side effects of treatment was introduced. The binding of the drug to the polymeric nanomaterial makes it possible to improve the biodistribution of the drug in the body and thereby reduce its toxicity, while often leading to a significant increase in anti-tumor activity. The application of the high-molecular-weight polymer nanomaterials and their drug conjugates in treatment utilizes the differences between healthy and tumor tissue. One of the important differencse is increased production of matrix metalloproteinases enzymes in the tumor microenvironment, which is mainly used to tumor site-controlled release of polymer- bound drug. Keywords: polymer nanomaterial, matrix metalloproteinase, release of the drug, penetration, EPR efect
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Noncanonical human eIF4Es in and out of the RNA granules
Frydrýšková, Klára ; Pospíšek, Martin (advisor) ; Půta, František (referee) ; Valášek, Leoš (referee)
Eukaryotic translation initiation factor eIF4E1 (eIF4E1) plays a pivotal role in the control of cap-dependent translation initiation, occurs in P- bodies and is important for the formation of stress granules (SG). Human cells encompass two other non-canonical translation initiation factors capable of cap binding although with a lower affinity for the cap: eIF4E2 and eIF4E3. Here, I investigated the ability of individual eIF4E family members and their variants to localize to SGs and P-bodies in stress-free, arsenite and heat shock conditions. Under all tested conditions, both eIF4E1 and eIF4E2 proteins and all their variants localized to P-bodies unlike eIF4E3 protein variants. Under both arsenite and heat stress conditions all tested variants of eIF4E1 and the variant eIF4E3-A localized to SGs albeit with different abilities. Protein eIF4E2 and all its investigated variants localized specifically to a major part of heat stress-induced stress granules. Further analysis showed that approximately 75% of heat stress-induced stress granules contain all three eIF4Es, while in 25% of them eIF4E2 is missing. Large ribosomal subunit protein L22 was found specifically enriched in arsenite induced SGs. Heat stress-induced re- localization of several proteins typical for P-bodies such as eIF4E2, DCP-1, AGO-2...
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