Autophagy, senescence and apoptosis are tightly linked processes which together determine the fate of cells in response to various stresses. There is ample evidence supporting the notion that senescent cells are highly dependent on autophagy and this process is here much more intensive than in nonsenescent cells. Autophagy may to some extent compensate increased energetic and metabolic demands of senescent cells and also helps with removal of toxic products such as oxidized proteins, protein aggregates and damaged organelles resulting from an overloaded metabolism of some senescent cells. In addition, some studies reported the need of autophagy for the adoption of senescent phenotype. However, there are also studies with seemingly contradictory results claiming that increased autophagy prevents or delays cellular senescence. Relationship of autophagy to apoptosis is similarly ambivalent. Whereas intact autophagy is necessary for the cell, while slightly increased autophagy still has a rather positive impact, excessive autophagy may lead to degradation of critical components necessary for cell function and survival and can trigger one of the modes of programmed cell death. In the first part of this work, we focused on the analysis of autophagic response in senescent and proliferating pancreatic...

Abstract The yeast Saccharomyces cerevisiae on solid media forms multicellular colonies. Cells within colonies undergo differentiation and metabolic diversification, including formation of two layers of cells called Upper and Lower cells. The metabolic activity of U and L cells is different. For instance a higher level of autophagy was observed in U cells. This thesis includes a literature review of molecular mechanisms of autophagy in yeasts. Yeast colonies, under starvation conditions, produce volatile ammonia signal. This signal allows them communicate over a distance. Studies, revealing cell differentiation within colonies and ammonia signalling among colonies, were performed in colonies of laboratory strains. Strains isolated from nature, so-called wild strains, form distinct structured colonies, termed fluffy. Yeast within fluffy colonies also form different cell types. However the situation seems to be more complex that within smooth colonies of laboratory strains. Strains were constructed during this study, which express marker proteins Icl2p, Pox1p, Mae1p, Pma1p, Pma2p, Ino1p, Met17p and Atg8p fused with fluorescent labels in order to study cell differentiation and other processes within fluffy colonies. Furthermore, a new system for ...

Charles University in Prague Pharmaceutical Faculty in Hradec Králové Department of Pharmacology and Toxicology Student: Anastasiya Shkut Supervisors: Mgr. Jana Mandíková, Virginia Motilva Ph.D. Title of diploma thesis: The role of melatonin in SIRT1 and p-AMPK regulation in HT-29 cell line. Sirituin 1 (SIRT1) is NAD+ dependent deacetylase present in wide range of organisms including mammals. It was found to extend life span in yeasts during calorie restriction (CR) conditions. SIRT1 deacetylates many regulator proteins and thus control metabolic status of cell as well as AMP-activated kinase (AMPK), which is also energy regulator enzyme depending on NAD+ levels in cell. Both of them play roles in cancer and could influence autophagy, although the exact mechanism remains unclear. We focused our study on hormone melatonin, which has anti-inflammatory and anti-cancer effects, to study its influence on human colon cancer cell line HT-29. If it has impact on SIRT1 and AMPK and what is hierarchic relationship between SIRT1 and AMPK. Also we observed its possible influence on autophagy. We used Western blotting (WB) technique and from our results it seems that melatonin has significant effect on SIRT1, which might activate AMPK as well as autophagy. Nevertheless some of results did not have sufficient...

Plant autophagy is a crucial evolutionary conserved process for recycling cytoplasmic material under stress conditions or during development. The autophagic pathway is negatively regulated by TOR kinase, a versatile molecule modulating a wide range of cellular processes. In mammals, TOR kinase may be activated by phosphatidic acid, a vital signalling lipid. This thesis aims to prove the possible involvement of phospholipids in plant autophagy. I analysed the rate of primary root inhibition in knock-out mutants coding phospholipases in A. thaliana with induced autophagy, measured activity of lipid metabolising enzymes in wild type and atg10 mutant and observed autophagosome formation in selected mutants. Autophagosomes were labelled by fluorescent protein in vivo and by indirect immunolabelling in fixed samples. Using advanced stereological approach, I optimized a method for obtaining an unbiased estimate of autophagosome number in plant root cells.

The exocyst, an octameric protein complex conserved among all eukaryotes, mediates tethering of the vesicle prior to its fusion with the target membrane. Apart from the function of exocyst in exocytosis, new studies from both mammalian and plant fields report its involvement in the cellular self-eating process called autophagy. In land plants the number of paralogs of some exocyst subunits is extraordinarily large. There are 23 paralogs of Exo70 subunit in Arabidopsis thaliana. It is supposed that these paralogs have acquired functional specialization during the evolution - including involvement in autophagy. Using yeast two- hybrid assay it is shown here that Exo70B1 and Exo70B2, but not other Arabidopsis Exo70 paralogs interact with Atg8, an autophagosomal marker. The proximity of these two paralogs and Atg8 in vivo was confirmed by independent Förster resonance energy transfer (FRET) method. Interestingly, interaction of Atg8f with Exo70B2 paralog appears to be stronger than with Exo70B1. Exo70B1-mRUBY expressed under the natural promoter shows punctate membrane structures that are mostly static. That changes after the tunicamycin treatment - movement of some of these dots was induced. Homology modeling of Exo70B1 and Exo70B2 proteins tertiary structure in combination with bioinformatic prediction based...

The mortality of cardiovascular diseases remains high and it likely tends to increase in the future. Although many ways how to increase the resistance against myocardial ischemia- reperfusion damage have been described, few of them were transferred into clinical practice. Cardioprotective effect of chronic hypoxia has been described during 60s of the last century. Its detailed mechanism has not been elucidated, but a number of components has been identified. One of these components presents protein kinase C (PKC). The role of PKC was described in detail in the mechanism of ischemic preconditioning, but its involvement in the mechanism of cardioprotection induced by chronic hypoxia remains unclear. One reason is the amount of PKC isoforms, which have often contradictory effects, and the diversity of hypoxic models used. The most frequently mentioned isoforms in connection with cardioprotection are PKCδ and PKCε. The aim of my thesis was to analyze changes in these PKC isoforms at two different cardioprotective models of hypoxia - intermittent hypobaric (IHH) and continuous normobaric hypoxia (CNH). We also examined the target proteins of PKCδ and PKCε after the adaptation to IHH, which could be involved in the mechanism of cardioprotection. These included proteins associated with apoptosis and...

Vandetanib, lenvatinib and cabozantinib are inhibitors of receptor tyrosine kinases approved to treat locally advanced or metastatic thyroid gland, kidney and liver cancers. These multi- kinase inhibitors, inhibit phosphorylation of tyrosine moieties of protein, thus modulate cell signalization in cancer cells. Metabolites of vandetanib, lenvatinib and cabozantinib were detected in vitro as well as in vivo in blood and urine. Cytochromes P450 and flavin monooxygenases were identified as primary enzymes participating in metabolism of these drugs. Literature lacks information regarding pharmacological efficacy of vandetanib, lenvatinib and cabozantinib metabolites. The aim of this diploma thesis was the investigation of pharmacological efficacy of N-oxides of vandetanib, lenvatinib and cabozantinib. The viability measurement under normoxic and hypoxic conditions was employed to determined their efficacy. The expression of enzymes of the first phase of xenobiotics metabolism (CYP 450 1A1, 1B1, 3A4 a CYP 450 oxidoreductase) and receptor tyrosine kinases RET and VEGFR2, as well as mechanism of changes in their expression were investigated using western blotting and flow cytometry. High performance liquid chromatography was utilised to investigate possible metabolism of tyrosine kinase inhibitors and...

Exocyst is an octameric protein complex, conserved across all Eukaryotes. Its role, originally described in yeast, resides in a tethering of the secretory vesicles to the plasma membrane prior to the membrane fusion of the two membranes. Subunits SEC3 and EXO70 are believed to be spatial landmarks for the vesicles delivery. While yeast genome encodes single EXO70, we find dozens of them in land plants (23 in Arabidopsis). This work is focused at a role of the exocyst complex in plant cells. Its first part documents, that exocyst is essential for delivery of the cell wall components, namely pectins, but also for pathogen induced secondary cell wall thickening. Second part reveals an unconventional role of EXO70B1 subunit harboring exocyst subcomplex at an autophagic pathway to the vacuole and raises many questions about plant secretory pathway.

Toll like receptors (TLRs) are germline-encoded pattern recognition receptors (PRRs) that play a central role in host cell recognition and responses to pathogens. Primarily they are responsible for induction and regulation of the innate and adaptive immune responses whereby the effector function is executed chiefly by differentiated myeloid cells. Somewhat unexpectedly, TLRs have been also shown to be involved in direct pathogen sensing by bone marrow-derived hematopoietic stem cells (HSCs) and hematopoietic progenitors when, under inflammatory conditions, the rapid generation of innate immune effector cells that effectively combat the infection is of utmost priority. While it has been recognized that the release of inflammatory cytokines from inflamed tissues along with the changes in proportions of differentiating cells in the bone marrow (BM) as well as the BM niche can nudge the differentiation of adult BM-derived cells towards myeloid cells and granulocytes, a direct role of TLRs expressed by HSCs in this process has been demonstrated only recently. However, whether a similar mechanism operates also during embryonic hematopoiesis is unknown. Here we show that TLRs and their adaptor proteins are functionally expressed during early stages of embryogenesis by short-lived maternally-transferred...

Exocyst is a binding protein complex, which is evolutionary conserved in yeast, animal and in plant cells. It has crucial role in regulation of cell morfogenesis and cell polarity. The function of the exocyst complex is binding of secretoric vesicle to the proper side on plasma membrane in penultimate step of exocytosis. This process is essecial for function and survival of cell. Another process crucial for the cell is autophagy. In plants autophagy plays important role in the responses to nutrient starvation, senescence, abiotic and biotic stress. RabG3b are small GTPases, which have positive role in autophagy. In this work I described the interaction between RabG3b and some of subunits of exocyst complex: Exo70B1, Exo70B2 and Exo84b. I also studied changes in morfogenesis of tonoplast by induction and inhibition of authophagy and induction of anthocyans synthesis in Arabidopsis thaliana.