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Role of Ccr4 deadenylase in cell cycle regulation in yeast colonies
Daumová, Lenka ; Čáp, Michal (advisor) ; Převorovský, Martin (referee)
Regulation of cellular processes is of key importance for survival of cells. Many regulations are mediated by the CCR4-Not complex, a highly conserved protein complex, which is present in eucaryotic cells, from yeast to mammals. In this work I study mostly the role of the Ccr4 subunit on yeast survival in the aging colony of Saccharomyces cerevisiae, mainly during cell cycle progression. Ccr4 si a deadenylase, and its main function is cleavage of poly(A) tail of mRNA molecules, and by doing so, shortening the mRNA life-time. It is very important during strictly regulated cellular processes, because it is essential that gene expression of specific genes happens only at specific time. Saccharomyces cerevisiae BY 4742 is a haploid yeast strain, which can easily be used for making deletion mutants in specific genes. In this diploma thesis I focus on studying a deletion mutant of CCR4, along with deletion of other genes, which influence yeast cell cycle. By comparing the phenotype of these mutants with wild type, it is possible to identify changes in phenotype, caused by these deletions, and their influence on yeast cell survival. Key words: cell processes regulation, CCR4-Not complex, Ccr4 subunit, cell cycle, yeast, Saccharomyces cerevisiae, gene deletion
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miRNA-mediated translational repression
Kučerová, Michaela ; Mašek, Tomáš (advisor) ; Beznosková, Petra (referee)
Recent models of miRNA-mediated translational repression favor initiation as the phase of translation, where the repression is primarily evoked. miRNA-induced silencing complex utilizes miRNA as a guide molecule to find its target mRNA. To inhibit mRNA translation and induce its decay, many other proteins are then recruited, e.g. GW182 protein, PAN2-PAN3 a CCR4-NOT deadenylation complexes, decapping enzyme and eIF4E-binding proteins. miRNA-mediated translational repression is then established by either their concerted action or their consecutive and coordinated binding to target mRNA. To date, several mechanisms have been described: GW182- mediated PABP displacement; GW182-independent translational repression; miRNA-mediated eIF4A1 dissociation or eIF4A2 recruitment; translational repression mediated by deadenylases CAF1 and CCR4; and 4E-T, eIF4E2, GIGYF2 translational repressor proteins recruitment. Here, I provide up-to-the-minute summarization of these mechanisms with the aim to extract any universality from them.
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