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Endoplasmic reticulum stress
Červenka, Jakub ; Schierová, Michaela (advisor) ; Horníková, Lenka (referee)
The accumulation of unfolded or misfolded proteins in endoplasmic reticulum (ER) leads to ER stress and the activation of unfolded protein response (UPR). Recent studies show that ER stress or UPR are associated with many diseases such as diabetes, hepatitis type C, prion disease, different kinds of tumors or Alzheimer's, Parkinson's and Huntington's disease and also with physiological processes like cell differentiation. When UPR is activated in yeast Saccharomyces cerevisiae, Ire1 protein oligomerizes, transautophosphorylates and activates itself. After this, Ire1 cleaves HAC1 mRNA to remove an intron. The spliced form of HAC1 mRNA is translated into the Hac1 transcription factor, which induces transcription of genes for chaperones of lumen ER, proteins involved in ERAD, synthesis of lipids etc. The cell uses this to reestablish homeostasis in ER. In mammals, the UPR is more complex and except Ire1 dependent pathway, it comprises Perk and Atf6 pathways, which are missing in yeast. Nevertheless, Perk is activated and regulated by the similar mechanism as Ire1 in S. cerevisiae. In consideration of broad spectrum of methods for genetic manipulation, rapid growth and well annotated genome, the yeast S. cerevisiae is a useful model for study of general mechanisms of UPR in mammals.
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Endoplasmic reticulum stress
Červenka, Jakub ; Schierová, Michaela (advisor) ; Horníková, Lenka (referee)
The accumulation of unfolded or misfolded proteins in endoplasmic reticulum (ER) leads to ER stress and the activation of unfolded protein response (UPR). Recent studies show that ER stress or UPR are associated with many diseases such as diabetes, hepatitis type C, prion disease, different kinds of tumors or Alzheimer's, Parkinson's and Huntington's disease and also with physiological processes like cell differentiation. When UPR is activated in yeast Saccharomyces cerevisiae, Ire1 protein oligomerizes, transautophosphorylates and activates itself. After this, Ire1 cleaves HAC1 mRNA to remove an intron. The spliced form of HAC1 mRNA is translated into the Hac1 transcription factor, which induces transcription of genes for chaperones of lumen ER, proteins involved in ERAD, synthesis of lipids etc. The cell uses this to reestablish homeostasis in ER. In mammals, the UPR is more complex and except Ire1 dependent pathway, it comprises Perk and Atf6 pathways, which are missing in yeast. Nevertheless, Perk is activated and regulated by the similar mechanism as Ire1 in S. cerevisiae. In consideration of broad spectrum of methods for genetic manipulation, rapid growth and well annotated genome, the yeast S. cerevisiae is a useful model for study of general mechanisms of UPR in mammals.
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Study of the performance of microbial MDR pumps by fluorescent probes: effect of potential inhibitors
Kodedová, Marie ; Gášková, Dana (advisor) ; Höfer, Milan (referee) ; Sychrová, Hana (referee)
The current increased use of antifungal agents has resulted in the development of resistance to these drugs. Search for new antifungals with different mechanisms of action overcoming the multidrug resistance is thus underway. Surface-active antifungals have the advantages of minimizing host toxicity and the emergence of drug resistance. We have developed a fluorescence method based on the use of the potentiometric fluorescent probe diS-C3(3), substrate of two major S. cerevisiae MDR pumps, Pdr5p and Snq2p. It allows us to monitor with high sensitivity and in real time changes in the activities of both pumps and also in membrane potential. We present here an efficient strategy for identifying pump inhibitors with minimal side effects on membrane integrity, and compare the potencies of different inhibitors towards MDR pumps. New efficient inhibitors of MDR pumps could potentially be used in conjunction with current antimicrobials that are MDR pump substrates. The method can be also used to determine the mechanism of action of surface-active drugs and their lowest effective concentrations.
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