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Study of mechanisms of Sertoli cell survival in xenogeneic organism
Porubská, Bianka ; Krulová, Magdaléna (advisor) ; Anděra, Ladislav (referee)
Sertoli cells (SCs) are somatic cells located in the testes. They are the only cells in direct contact with germ cells and play a key role in process of spermatogenesis. New insights in the biology of SCs are highlighting the immunological function of these cells: germ cells protection by maintaining the immunoprotective niche, creating the blood- testis barrier and local modulation of the immune response to spermatic cells. Immunomodulatory activity of SCs is preserved after their allo- and xenogeneic transplantation, and thus SCs prolongs survival not only of themselves but also of cells transplanted with them. The aim of this thesis was to study the survival and migration of SCs precursors (TSC) in mice recipients. The project is employing the neonatal tolerance phenomenon and evolutionary distinct donor organism, Xenopus tropicalis, to monitor conserved mechanisms of immune system (IS) modulation using SCs. SCs were detectable in the lungs and thymus 7 days after transplantation. The phenotype of immune cells was not altered 30 days after transplantation, however we detected changes in cytokine environment, namely increased levels of cytokines typical for Th2 and Treg immune responses. In vitro experiments further confirmed IS modulation by SCs - changing the phenotype of macrophages to alternatively...
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Activation and regulation of cell death in senescent cancer cells.
Holíček, Peter ; Anděra, Ladislav (advisor) ; Drbal, Karel (referee)
Cellular senescence is a distinct cell state, characteristic by cessation of cell proliferation and it is accompanied by specific morphological and biochemical alterations. Increasing and persisting incidence of senescence cells has been shown to have detrimental effect on an organism largely contributing to its ageing. Senescent cells also positively support tumour growth and can even stimulate carcinogenic transformation of surrounding cells. Moreover, senescence can be induced even in tumour cells spontaneously or by chemotherapy. Regardless of an initial stimuli and type of cells, there are two main senescence inducing pathways p16/pRb and p53/p21. Both senescent cells as well as senescent cancer cells seems to have modified apoptotic signalling at the level of mitochondria and Bcl-2 family proteins. In this study, we aimed to analyse effect of senescent state as well as pre-senescent (growth arrested state) induced by p16/pRb and p53/p21 signalling pathways on the response of H28 mesothelioma cancer cells-derived clonal cultures to various cell death-inducing stimuli. By inducible expression of p16 and p21 proteins in doxycycline-dependent manner, we forced cells to acquire senescent-like phenotype, which we detailly characterised. Our results showed that senescent-like phenotype, manifests...
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Caspase-8 - a multifunctional protease at the intersection of apoptosis and necrosis
Davídková, Daniela ; Anděra, Ladislav (advisor) ; Doubravská, Lenka (referee)
Caspase-8 is classified as an initiator caspase especially of death receptors-induced apoptosis. It is expressed in all tissues and depending on its regulatory circuits it plays an important role not only in the signalization of apoptosis but also in necroptosis, cell survival and other cellular processes. Its proper function is irreplaceable in general proliferation, differentiation and development, in the function of immune responses and thus maintenance of homeostasis. Its malfunction or absence is manifested by defects in both cells and organisms and it is connected with serious diseases such as cancer. This thesis summarizes the knowledge of ways of regulation and function of caspase-8 in these processes. Key words: caspases, apoptosis, necrosis, necroptosis, DISC, activation complex
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Analysis of cell signaling mediated by the adapter protein Daxx
Švadlenka, Jan ; Anděra, Ladislav (advisor) ; Forstová, Jitka (referee) ; Stopka, Tomáš (referee)
2 Abstract Multifunctional adapter protein and histone chaperone Daxx has been described in nu- merous cellular processes, including the regulation of apoptotic and stress signalling, antiviral response and processes connected to chromatin (e. g. transcription). Its influ- ence on chromatin-related processes is mainly carried out by several associated en- zymes, such as DNA-methyltransferase-1, histone deacetylases and chromatin- remodelling ATPase ATRX. In the complex with ATRX Daxx functions as a chaperone of histone-3.3, maintaining the constitutive heterochromatin e. g. at centromeric and telomeric regions. The main aim of this Thesis was a better understanding of the Daxx cellular functions through identification and functional characterization of its novel interacting proteins. Using the yeast two-hybrid screen, several such new Daxx-interacting proteins were identified. These proteins were mainly nuclear, connected to the regulation of chroma- tin-related processes. More detailed analysis focused on the interaction of Daxx with chromatin-remodelling ATPase Brg1. This interaction was confirmed both in vitro and in the cells, where Daxx and Brg1 associated mainly in high molecular weight pro- tein complexes. These likely chromatin-remodelling complexes contain, in addition to Brg1, several...
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Posttranslational modification of the adapter protein DAXX in the cellular response to genotoxic stress
Bražina, Jan ; Anděra, Ladislav (advisor) ; Černý, Jan (referee) ; Vodička, Pavel (referee)
Maintaining the chromosome continuity and complete genetic information in human cells is crucial for cell survival and the whole organism. It prevents life-threatening pathologies and preserves genetic continuity. However, cellular DNA is exposed to both endogenous and exogenous stress damaging its content and integrity. This stress activates mechanisms involving detection and repair of these damaged sites (DDR). One of the most serious types of DNA damage double-stranded breaks (DSB) occuring when both strands are severed. DSBs trigger wave of PTMs that regulate protein interactions, nuclear localization and catalytic activity of hundreds of proteins. Such modifications include acetylation, methylation, SUMOylation, ubiquitinylation and especially phosphorylation. The most important kinases involved in DDR kinases are ATM, ATR and DNA-PK. These kinases are activated immediately after the detection of the damaged area. DAXX (Death-associated protein 6) is an adapter and predominantly nuclear protein, which is involved in chromatin remodeling, gene expression modulation, antiviral response and depositing histone H3.3 variants into chromatin or telomeres. Daxx is essential for murine embryogenesis, since the homozygous deletion is lethal in E9.5-10. In 2006 a study mapping the substrates of kinases...
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Role of cFLIP/CFLAR protein in the activation and regulation of cell death
Ksandrová, Marie ; Anděra, Ladislav (advisor) ; Macůrková, Marie (referee)
Programmed cell death as a natural mechanism plays essential role in development and homeostasis maintenance through removal of damaged, unwanted or dangerous cells. The cell death is an irreversible proces must be strictly regulated and thus defects in the regulation of cell death could lead to serious/fatal diseases. There are also one of the reasons why cell death regulating mechanisms are subjects of intense research nowadays. c-FLIP is one of several important cell death regulators. Three distinct isoforms of c-FLIP were detected on the protein level in human organism (long c-FLIPL and two shorter variants c-FLIPS and c-FLIPR) that interact their main cellular partner procaspase 8. The functional consequences of their interaction (enhancement or suppression of procaspase 8 selfprocessing) depend on the cellular level of c-FLIP, expressed splice variants and extracellular signaling. As c-FLIP is an important component of cell death signaling pathways (apoptosis and regulated necrosis), its expression and functional posttranslational modifications are strictly regulated by several mechanisms. Upregulation of c-FLIP levels has been found in various types of tumor cells that are often resistant to anticancer treatment.
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Activation of the initiation caspases and regulation of their activity
Votavová, Barbora ; Anděra, Ladislav (advisor) ; Černý, Jan (referee)
Caspases are the key proteins participating in both activation and execution of apoptosis. Extrinsic or intrinsic apoptotic signaling leads to sequential activation of the initiation and execution caspases. Activation of initiator caspases is mediated by their processing in multiprotein complexes and activated initiator caspases then specifically cleave and thus activate the effector caspases. These then cleave a number of structural and functional proteins, which consequently leads to cellular selfdestruction and its breakdown to apoptotic bodies. Considering the fundamental significance of the initiation of apoptosis, the activation as well as the activity of initiator (but also effector) caspases is strictly regulated at several levels. Primary the intensity and character of the recieved signal is crucial for the effective formation of the caspase activation complex. Then the concentration of intracellular ionts, nucleotides and various proteins (proteins from the Bcl-2 family, inhibitors of apoptosis (IAPs), heat shock proteins,…) can also highly influence individual steps of caspase activation. Caspases themself can be posttranslationally modified (phosphorylated, ubiquitylated,…) and their activity can be either suppressed or also enhanced. All these processes form complex regulatory network serving...
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