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Structural characterization of interactions between subunits of the GBAF chromatin remodeling complex
Naušová, Karolína ; Veverka, Václav (advisor) ; Rozbeský, Daniel (referee)
Epigenetics investigates heritable phenotypic changes that are not caused by alterations in DNA sequence. One of the major epigenetic tools is chromatin remodeling mediated by ATP-dependent chromatin remodeling complexes, which fundamentally affect gene expression and thus cellular fate. A mammalian variant of the ATP-dependent chromatin remodeling SWI/SNF complex is the BAF complex, which is involved in both activation and repression of gene expression. There have been identified three major variants of BAF complex one of which is non-canonical BAF, also known as GLTSCR1 containing BAF, GBAF. Each complex consists of up to 15 subunits, some of which are specific only to one of the complex variants. Mutations in genes coding subunits of BAF lead to several genetic disorders or to the cancer development. The GBAF complex contains specific subunits, BRD9 (Bromodomain containing protein 9), GLTSCR1 (Glioma tumor suppressor candidate region 1) and GLTSCR1L (GLTSCR1-like), which are essential for its formation. Although the exact function of the GBAF complex has not been elucidated yet, it is often associated with synovial sarcoma and rhabdoid tumors. Two of the three complexes are impaired in those tumors and gene expression is maintained only due to the GBAF complex. If GBAF would additionally loose...
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Methylation profile in malignancy
Stojčeva, Nina ; Vodička, Pavel (advisor) ; Vondrejs, Vladimír (referee)
Epigenetic changes represent chemical modifications of the DNA molecule and histone proteins by which gene expression is altered. Among them, DNA methylation is a known mechanism of silencing of tumor-suppressor and DNA repair genes, with an important role in carcinogenesis. Many studies have been done in order to identify the methylation signatures of these genes in different types of cancer. In our study, we investigated the methylation status of promoter regions of eight mismatch repair genes (MLH1, MSH2, MSH3, MLH3, PMS1, PMS2, MSH6 and EXO1) in 45 sporadic colorectal cancer cases and 12 head and neck cancer patients. Two out of eight genes, MLH1 and MLH3, exhibited promoter methylation. The results from both groups of patients were concordant. We summarize that the methylation profiles of MLH1 and MLH3 promoters could be potential candidates for epigenetic biomarkers in colorectal cancer, and eventually in head and neck cancer. Further investigations, which would confirm this theory, should be carried out.
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Mechanisms of action of bisphenol A with emphasis on metabolism and fertility
Houška, Jakub ; Daňková, Pavlína (advisor) ; Novák, Jan (referee)
Bisphenol A is an endocrine disruptor, a chemical which is found in environment and also in water and food consumed by people and which disrupts endocrine system of humans and other organisms. Being endocrine disruptor it has a wide scale of negative effects on human health. I have attempted reviewing the molecular mechanism of its action with special respect to obesity and reproduction in this paper including interactions of bisphenol with specific receptors, its impact on enzyme synthesis and also on epigenetic mechanisms as DNA methylation or changes in miRNA expression. Possible ways of elimination of bisphenol A effects are examined in the end of this work. Keywords bisphenol A, molecular mechanisms, obesity, fertility, receptor, epigenetic mechanisms, elimination of effects
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Detailed characterization of the interaction between LEDGF/p75 and MeCP2
Naušová, Karolína ; Veverka, Václav (advisor) ; Hrabal, Richard (referee)
Epigenetics investigates heritable phenotype changes that are not caused by alternations in DNA sequence. Major epigenetic mechanisms include covalent DNA modifications (particularly methylation), histone and chromatin modifications and RNA interference. These mechanisms are involved in number of processes from transcription to translation. Lens epithelium-derived growth factor (LEDGF/p75) is ubiquitously expressed in human body and it is considered to be a transcriptional coactivator upregulated upon stress conditions. LEDGF/p75 consists of several domains. The N-terminal PWWP domain plays very important role from epigenetic point of view as it is able to bind di- and trimethylated lysine 36 of histone 3, which is considered as an epigenetic marker of transcriptionally active chromatin. LEDGF/p75 interaction partners include e.g. HIV integrase, MLL1-MENIN complex or MeCP2. A shorter isoform of LEDGF/p75 called LEDGF/p52 shares with LEDGF/p75 its N- terminal part that is responsible for interaction with DNA and chromatin. Methyl-CpG-binding protein 2 (MeCP2) is present everywhere in human body with the highest abundance in brain. MeCP2 is a transcriptional modulator remodelling chromatin, therefore its function is to activate or repress gene depending on the molecular and cellular context. Among...
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Epigenetics mechanisms
Šornová, Veronika ; Černá, Marie (advisor) ; Koc, Michal (referee)
Epigenetics is the study of heritable changes in gene activities that are not caused by changes in the DNA sequence. Epigenetic mechanisms can be employed at many levels, from transcription to translation. They include DNA methylation, histone modification, and with it connected chromatin modification, and RNA interference. The result is the change of chromatin conformation leading to decrease or increase of certain gene expression, X-chromosome inactivation or gene imprinting. Epigenetic regulation plays important role in etiopatogenesis of multifactorial diseases. Genetic predisposing factors (in autoimmune diseases there are genes of major histocompatibility complex) and environmental factors, which affect our genome just through epigenetic modifications, are involved in their manifestation. Key words: Epigenetic mechanisms, DNA methylation, histone modification, RNA interference, genomic imprinting, X-chromosome inactivation, multifactorial disease.
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Methylation profile in malignancy
Stojčeva, Nina ; Vodička, Pavel (advisor) ; Vondrejs, Vladimír (referee)
Epigenetic changes represent chemical modifications of the DNA molecule and histone proteins by which gene expression is altered. Among them, DNA methylation is a known mechanism of silencing of tumor-suppressor and DNA repair genes, with an important role in carcinogenesis. Many studies have been done in order to identify the methylation signatures of these genes in different types of cancer. In our study, we investigated the methylation status of promoter regions of eight mismatch repair genes (MLH1, MSH2, MSH3, MLH3, PMS1, PMS2, MSH6 and EXO1) in 45 sporadic colorectal cancer cases and 12 head and neck cancer patients. Two out of eight genes, MLH1 and MLH3, exhibited promoter methylation. The results from both groups of patients were concordant. We summarize that the methylation profiles of MLH1 and MLH3 promoters could be potential candidates for epigenetic biomarkers in colorectal cancer, and eventually in head and neck cancer. Further investigations, which would confirm this theory, should be carried out.
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