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The role of stress granules and 4E-BP in heat-stressed cells of S. cerevisiae
Kolářová, Věra ; Hašek, Jiří (advisor) ; Zimmermannová, Olga (referee)
The cells are capable of very quick and specific reactions on stress conditions. Influence of translation, specifically initiation of translation by inhibition factors, is one of the main regulatory process. Two of eIF4E-binding proteins (4E-BP), Eap1p and Caf20p, are known as cap-dependent translation repressors in yeast Saccharomyces cerevisiae. We used in vivo fluorescent microscopy analysis to show different reaction of Caf20p and Eap1p to heat stress. Protein Caf20p does not react on heat shock and stays difused in cytoplasm. Contrary to Caf20p reaction, protein Eap1p accumulates in cytoplasm close to stress granules (SGs). This work shows that Eap1p is involved in stress granules assembly. In the absence of Eap1p, yeast cells react to the heat stress with small and less focused SGs. Dele- tion of CAF20 does not affect SG assembly. This points to specific function of SG in distribution of factors connected with stress reaction. Polysomal analysis shows that deletion of one of initiation translation repressors does not affect heat induced global repression of translation. In permisive condition deletion of EAP1 may cause defect in addition of 60S ribosomal subunits. Absence of protein Eap1p causes morphological defect. That point to a different reactions of Eap1p and Caf20p on heat stress and possible...
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Protein diversity in human stress granules
Kráčmarová, Jana ; Frydrýšková, Klára (advisor) ; Motlová, Lucia (referee)
During unfavourable conditions eukaryotic cells inhibit translation of certain mRNAs and preferably synthesize proteins that are involved in the stress response. The saved energy is used for repair of cellular damages. The untranslated mRNAs are accumulated in the form of ribonucleoprotein complexes. This accumulation results in the formation of the cytoplasmic stress granules. These granules are sites of structure remodeling and triage of the ribonucleoprotein complexes - they can be stored, degraded or sent back to the cytoplasm for translation reinitiation. The mRNA molecules carry their associated proteins, which include also proteins implicated in the cell signaling. Stress granules can thus indirectly regulate some processes, such as apoptosis, and play role in the survival of the cell. This thesis focuses on protein content of stress granules in human cell lines, briefly characterizes stress factors that induce their formation and discusses differences between the content of stress granules induced by different stress stimuli. An important part of this thesis is a table summarizing proteins found in the stress granules. The second part of this work is dedicated to the characterization of the proteins of the fragile X mental retardation protein family. It outlines the possible link between...
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The characteristics of stress granules in yeast Saccharomyces cerevisiae
Slabá, Renata ; Hašek, Jiří (advisor) ; Binarová, Pavla (referee)
9 ABSTRACT For proper function proteins should have a native conformation. If their conformation is impaired due to environmental stress or genetic mutation, proteins become prone to aggregation. There exist various types of protein aggregates. Stable non-membraneous inclusions can form which can serve for clearance of aberrant proteins from place where they can interfere with essential cellular processes. Another type of aggregates can serve as transient deposits of proteins thus protecting them from stress conditions. Stress granules (SG) are a such example of transient granules. Their formation is induced by heat shock for example. SGs contain mRNA, components of translation machinery, and other proteins. One of these proteins is Mmi1, small highly conserved protein with unknown function. Association of Mmi1 with stress granules and partial co-localization with chaperon Cdc48 and proteasom indicates Mmi1 can mediate heat stress damaged protein degradation. We have uncovered that yeast prion protein Sup35 is a component of stress granules as well. With regard to its aggregation capability there existed an assumption that prion domain of Sup35 could serve as scaffold for SG assembly. However as we show deletion of prion domain of Sup35 protein does not affect stress granules formation dynamics. Yeast...
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