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Molecular mechanisms of carcinogenic effects of alcohol
Vepřková, Jana ; Kábelová, Adéla (advisor) ; Novotná, Božena (referee)
Alcohol (ethanol) enters the human body mainly through ingestion of alcoholic beverages and its chronic consumption is considered a worldwide socio-economic problem. Besides others, alcohol consumption increases the risk of development of breast, liver, colorectal and upper aerodigestive tract cancer. In the liver, ethanol is metabolised into toxic acetaldehyde which is the main cause of DNA damage leading to cancer development. Acetaldehyde covalently interacts with nucleotides in the DNA forming DNA adducts such as N2 -ethylidene-2'-deoxyguanosine or S- and R-α-methyl-γ-hydroxy-1,N2 - propano-2′-deoxyguanosine. Acetaldehyde can also interact with proteins and disrupt their function. Ethanol metabolism by cytochrome P450 2E1 leads to production of reactive oxygen species, that subsequently damage cellular molecules such as lipides and DNA. Ethanol also initiates carcinogenesis through aberant DNA methylation or interference with retinoic acid metabolism. In cancer development, alcohol interacts with other environmental and genetic factors, which can increase the risk of developing cancer in predisposed individuals.
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Improved demethylation in ecological epigenetic experiments: Testing a simple and harmless foliar demethylation application
DVOŘÁKOVÁ, Hana
Spray application of 5azacytidine on established plant seedlings was tested for its demethylating efficiency. It represents a novel method for plant experimental demethylation with a potentially lower negative impact on plant development compared to the traditional application of the demethylating agent through germination of seeds in its solution. Further, the 5azacytidine spray application was used in practice to erase the epigenetic memory in offspring of Taraxacum brevicorniculatum plants from different competitive conditions. The impact of parental competition on the juvenile phenotype was estimated by measuring growth related traits, while the experimental demethylation allowed for evaluating the significance of DNA methylation marks in bioticaly induced transgenerational effects in T. brevirorniculatum.
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Epigenetic control of PU.1 gene transcription during development of 5-Azacytidine resistance in acute myeloid leukemia
Křtěnová, Petra ; Burda, Pavel (advisor) ; Čuřík, Nikola (referee)
Hematopoiesis is a highly orchestrated process, in which a single hematopoietic stem cell (HSC) gives a rise to all blood cellular components. For myeloid and lymphoid development precise controlled expression of the PU.1 transcription factor is needed. Deletion of PU.1 gene in mouse is lethal and its dysregulation during hematopoietic differentiation is associated with blood malignancies including acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). MDS and AML are serious blood disorders characterized by expansion of immature blood cells and lack of differentiated functional cells. Not only genetic but also epigenetic aberrations represent a very important field for studying pathophysiology of leukemia genesis and dysregulation of the PU.1 gene represents intensively studied candidate mechanism. Modern therapy of selected MDS and subset of AML patients is based on treatment with DNA hypomethylating agent Azacytidine (AZA) interfering in PU.1 gene regulatory mechanism. However, poor response or resistance to this therapy often occurs. In this thesis we present data obtained from AZA-resistant clones of MDS/AML cell line OCI-M2. We analysed DNA methylation and DNA hydroxymethylation at the key regulatory element of the PU.1 gene (URE). We found that these epigenetic modifications at URE...
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Association of chromatin modifications with transgenerational abiotic stress memory of plants
Vyskočilová, Barbara ; Holá, Dana (advisor) ; Fischer, Lukáš (referee)
Plants are constantly exposed to various stressors which usually leads to changes in the expression of many different genes. This can be controlled at multiple levels, including modifications of chromatin structure. Some of these modifications may persist even after the period when the plant is exposed to stress and could possibly act as a kind of "stress memory". This work deals with so-called meiotic/transgeneration "stress memory" of plants caused by abiotic stressors. Compilation of studies dealing with this topic showed that they are still rather rare and usually originated from only a few laboratories. The majority of these studies was aimed only at the examination of DNA methylation and their design was not always optimal. In my opinion, true proofs of transgeneration "stress memory" of plants still remain to be presented; further, more properly designed studies are necessary. Powered by TCPDF (www.tcpdf.org)
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Epigenetic mechanisms in the interferon γ signalling pathway
Fišerová, Lenka ; Reiniš, Milan (advisor) ; Javorková, Eliška (referee)
IFNγ is an important cytosine mediating imune responses, including antitumor immunity. It can affect expression of a lot of genes, which regulate different cellular processes. In tumor cells defects in signal cascade of IFNγ and mistakes in expression of genes regulated by IFNγ, for example genes for antigen adjustment and presentation (APM) or genes for major histocompatibility complex (MHC), were observed. Epigenetic mechanisms, can play a role in regulation of expression of genes for IFNγ, as well as in regulation of expression of genes regulated by IFNγ, including the components of the IFNγ signalling pathway. In lymphocytes from tumors the ability to produce IFNγ was limited by epigenetic silencing of genes for IFNγ. In tumor cells, epigenetic silencing of genes regulated by IFNγ, of genes of the IFNγ signaling cascade, for example IRF transcription factors, and other genes regulated by IFNγ, such as genes for APM, MHC or indoldioxygenase coding genes (IDO), was demonstrated. In case of their activation by IFNγ, epigenetic changes in regulation sequences of appropriate genes, were observed. IFNγ thus can be considered as an epigenetic agent. Epigenetic modulators are able to activate expression of genes regulated by IFNγ. By this way it's possible to explain some of immunomudullatory effects...
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Epigenetic regulation of HLA class II genes in relation to senescence of organism
Říhová, Adéla ; Kotrbová - Kozak, Anna Katarzyna (advisor) ; Slavčev, Antonij (referee)
Introduction: Glycoproteins of the major histocompatibility complex (MHC) are an irreplaceable part of immune response regulation and immune homeostasis maintenance. The regulation of the expression plays an important role in adaptive immune response. Recently, DNA methylation in regulatory areas, crucial for DNA availability to transcription factors, is one of the most researched mechanisms of this type of regulation. The DNA methylation is, among others, related to the aging processes. Increased predisposition age-related immunosenescence in higher age could result from the changes in methylation status of regulatory areas of MHC class II genes. Aims: The aim of this thesis is to analyze the methylation status of regulatory areas of DQB1 gene and to compare the differences between generations and specific alleles. The differences in the levels of DQB1 gene mRNA transcription between generations and specific alleles is also compared. Methods: Both DNA and RNA were isolated from blood samples obtained from donors of three different age groups. DNA was genotypized and modified by bisulfite conversion. The regulatory areas of DQB1 genes were then amplified and subcloned into bacteria. The positive clones were selected and subjected to DNA methylation analysis. RNA was reverse transcribed into cDNA...
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Nuclear magnetic resonance study of local changes in DNA double-helix stability induced by cytosine methylation
Socha, Ondřej ; Římal, Václav (advisor) ; Kouřilová, Hana (referee)
Cytosine methylation in CpG dinucleotides plays an important role in regulation of gene expression and cell differentiation. The structure of DNA double-helix is only weakly affected by cytosine methylation in CpG containing oligonucleotides, but a significant change of the duplex stability is caused. In this thesis, the melting preoperties of two self-complementary oligonucleotides CAAC GTTG and CAAm5C GTTG are studied using nuclear magnetic resonance spectroscopy. We measured 1H spectra at temperature range (276-350)K. The equilibrium and kinetic parameters of chemical exchange between duplexes and single strands were obtained by fitting the spectral lineshapes. Methylation of cytosine in the central CpG dinucleotide increases the melting temperature of each base pair. Thus, a high degree of cooperativity during chemical exchange is observed in our samples. Powered by TCPDF (www.tcpdf.org)
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Epigenetické regulace u autoimunitních onemocnění se zaměřením na revmatoidní artritidu
Horková, Veronika ; Daňková, Pavlína (advisor) ; Hušáková, Markéta (referee)
Exact cause of rheumatoid arthritis, as well as other autoimmune diseases has not been identified yet. In last twenty years, epigenetics showed a new face of immune system. DNA methylation, modification of histones - proteins around which DNA is wrapped, or interference of small RNA sequences - microRNAs, these all are heritable changes outside the DNA sequence that provide another component involved in autoimmunity. Presented epigenetic mechanisms alter gene expression and thus facilitate production of pro- inflammatory factors leading to autoimmune reactions. Moreover, genes regulating apoptosis are also frequently targeted by epigenetic modifications. Not only these mechanisms provide another level of immune defense, they also explain higher female susceptibility to autoimmune diseases and the influence of environment on pathogenesis of these diseases.
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Chromatin modifications in association with priming phenomenon in plants
Marková, Hana ; Holá, Dana (advisor) ; Fischer, Lukáš (referee)
Plants are exposed to many stressors to which they must be able to adapt. It has been found that plants can memorize the respective stress response and may respond to a subsequent stress exposure faster and to a greater extent. The mechanism of this so-called priming could be associated with the changes in the levels of chromatin modifications. Chromatin modifications are usually dynamically changing during the stress reaction. Some of these changes could persist for some time, thus the specific stress memory, mitotically and meiotically transmissible, could be established. Such a phenomenon was observed for stress caused by dehydration, salinity, mechanical damage, a combination of various stressors and a systemic resistance to pathogenic bacteria. So far, only a few studies on this topic exist; but even now it is clear that there are differences in the response of specific genes as well as the dependence on the length of the stress stimulus and the duration of the period between the first and second stress. A major disadvantage of existing studies is that they focus solely on histone modifications. Regarding the chromatin modifications studied so far, H3K4me3 could serve as the main mark for such priming. On the other hand, H3K27me3 modification is apparently not used as a memory tag. However, it is still...
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