|
|
Epigenetic mechanisms in the regulation of the B7-H1 and IRF-1 expression in tumour cells.
Hrušková, Veronika ; Reiniš, Milan (advisor) ; Krulová, Magdaléna (referee)
Interferon γ is an important T-cell helper type 1 (Th1) cytokine involves in antimicrobial immunity. It is a part of the inflammatory immune response in the site of infection. However, for its proper function, the regulation of immunity is necessary to avoid injury of the tissue caused by long-term inflammation. While interferon γ triggers expression of proinflammatory genes, it also regulates genes which inactivate immune response. The B7-H1 molecule belongs among these inhibitory regulators. Furthermore, antitumour effect of interferon γ is well-known as well. After extensive experiments, interferon γ was tested as an immunotherapeutic drug against melanomas in clinical trials. However, the trials had to be terminated prematurely because of unsuccessful results. It started to be clear that interferon γ could have also a protumour effect. Interferon γ upregulates the expression of B7-H1 molecule which aids tumour in escape from immunity. The B7-H1 molecule possesses a binding site for interferon regulatory factor 1 (IRF-1) in its promoter region. This IRF-1 is induced by interferon γ - JAK/STAT signalling pathway. In our previous research, we observed interferon γ induced DNA demethylation of promoters in genes that are involved in antigen presenting machinery. Additionally, DNA methylation of...
|
|
|
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.
|
|
|
Forensic analysis of epigenetic factors and mRNA
Andreasová, Karolina ; Šimková, Halina (advisor) ; Zachová, Markéta (referee)
In last years, forensic genetics focused on a research of epigenetic factors and mRNA. It turned out that their analysis provides valuable information that can be obtained from a small amount of a biological trace and which included e.g. estimation of circumstances of death, age estimation, discrimination within monozygotic twins, identification of tissues and body fluids, sample authentication, determination of paternal allele, etc. In this thesis, it is discussed methods of epigenetic factors and mRNA analysis and their potential application in future forensic practice.
|
|
|
Human endogenous retrovirus ERVWE1: transcriptional activation and modifications of promoter DNA methylation
Dobšová, Martina ; Trejbalová, Kateřina (advisor) ; Španielová, Hana (referee)
Endogenous retrovirus ERVWE1 is an integral part of the human genome. In the course of evolution, a protein encoded by the env gene of this retrovirus - Syncytin-1 - has gained unique function in human development. It mediates cell-to-cell fusion of placental cytotrophoblasts. Receptor that binds to Syncytin-1 is expressed in different cell types. Syncytin-1-mediated fusion is essential in placenta, but it can cause disruption of tissue integrity in other cell types. ERVWE1 expression is regulated by promoter DNA methylation, transcription factor GCM1 and efficient mRNA splicing. This thesis concerns the ERVWE1 expression and its regulation in non-placental tissues. It was found out that the moderate GCM1 overexpression was not sufficient to induce Syncytin-1 expression. Neither treatment with DNA demethylation agent 5-azacytidine nor with Syncytin-1 activator forskolin was able to manage Syncytin-1 expression. This thesis extends previous findings concerning high syncytin-1 expression in seminomas. In same tissues, there was found elevated TET1 expression on mRNA level in comparison with controls. The presence of the TET1 demethylation enzyme can influence ERVWE1 promoter DNA methylation. Previously unreported splicing variant of TET1 has been found during the construction of human TET1 expression...
|
|
|
Molecular characterisation of novel subtype of Acute lymphoblastic leukemia with lineage switch during early phase of treatment
Dobiášová, Alena ; Fišer, Karel (advisor) ; Novotný, Marian (referee)
Leukemia is the most common malignant disease in children patients. In our laboratory (CLIP) a novel subtype of B-cell precursor Acute Lymphoblastic Leukemia (BCP-ALL) with lineage switch during early phase of treatment towards myeloid lineage (swALL) was recently documented. SwALL incidence is almost 4 % of all BCP-ALLs (Slámová et al., 2014). DNA methylation (presence of 5-methylcytosine) is together with post-translational histone modifications and non- coding RNAs an epigenetic mechanism which regulates gene expression without changes of genetic code. DNA methylation is easily detected by bisulphite conversion and subsequent sequencing. The aim of this work was to compare genome-wide DNA methylation patterns between patients with swALL and control BCP-ALLs. The first step in achieving that was revision and improvement of bioinformatic processing protocol for eRRBS data from massive parallel sequencing. To improve the sequence adapter trimming I tested four bioinformatic tools - FAR, cutadapt, Trimmomatic and fastx_clipper. I implemented the fastest and most effective - Trimmomatic into the processing protocol. As a next step I analysed the data with improved protocol and extended the analysis in R programming environment where the comparison of studied groups was performed. The comparison of...
|
|
|
Role of the FTO gene in the genetic determination of common multifactorial diseases
Dlouhá, Dana ; Hubáček, Jaroslav (advisor) ; Černá, Marie (referee) ; Rossmeislová, Lenka (referee)
Obesity is a risk factor for development of cardiovascular disease, diabetes type 2 and some cancers. Newly detected genetic risk factor for body weight is the FTO gene ("fat mass and obesity associated"). The aim of this thesis was determine 1) whether the presence of risk alleles correlate with BMI in Czech population and to determine 2) whether there is an association between variants in the FTO gene and risk of myocardial infarction/ acute coronary syndrome (MI/ ACS), 3) renal failure (ESRD), or 4) incidence of colorectal cancer (CRC). We analyzed polymorphisms rs17817449 (first intron) and rs17818902 (3rd intron) using by PCR-RFLP and then also RT PCR. We found an association of the first intron variant (but not the 3rd one) and BMI in Czech control population. We have detected an association of 1st intron SNP and BMI changes during the intervention study in obese children, but not in obese females. We found a correlation between the risk allele and increased risk of ACS (OR 1.49) in patients with MI. In patients with ESRD was detected association between the risk allele and the risk of disease (OR 1.37). We didn't confirmed the association between rs17817449 and the development of CRC. Representative selected groups of the Czech populations "MONICA" and "HAPPIE" were used as controls. One...
|
|
|
DNA methyltransferase inhibitors and their effect on the activation of genes being of importance to a presentation of the antigen in tumour cells
Cebová, Magdaléna ; Reiniš, Milan (advisor) ; Poljaková, Jitka (referee)
DNA methylation is one of the epigenetic modulations that can be associated with tumour diseases. DNA methyltransferases act as catalysers of the process of DNA methylation and their inhibition could be used as a possible approach to the therapy of tumours. DNA methyltransferase inhibitors are classified into two groups, nucleoside inhibitors that are incorporated into DNA and subsequently form covalent bonds with DNA methyltransferase, and non-nucleoside inhibitors whose action is limited to inhibiting the catalytic site of the DNA methyltransferase. The first objective of this bachelor thesis was to compare the toxicity of DNA methyltransferase inhibitors in mouse tumour cell lines. The results show that the toxicity of nucleoside inhibitors is much higher (due to their incorporation into the DNA) than that of non-nucleoside inhibitors. The second objective was to compare the effect of DNA methyltransferase inhibitors on the expression of MHC (major histoncompatibility complex) class I glycoproteins on the surface of mouse tumour cells. Reduced expression of MHC class I glycoproteins is known to be one of the mechanisms used by the tumour cells to escape the immune system. Our laboratory has shown that some inhibitors (5-azacytidine) increase the expression of MHC I class molecules in MHC...
|
|
|
RNA directed DNA methylation in Arabidopsis thaliana
Motylová, Šárka ; Fischer, Lukáš (advisor) ; Moravec, Tomáš (referee)
The differential transcriptional activity of the genome is provided by epigenetic modifications, which include DNA methylation, alteration of histone N-terminal amino acids and changes in histone variants. RNA interference is a regulatory process, in which transcriptional or post-transcriptional silencing of exogenous or endogenous sequences is mediated by the action of small RNAs derived from these sequences. The 24-nucleotide siRNAs, forming a fraction of small RNAs, direct de novo DNA methylation and participate in the maintenance of DNA methylation (RNA-directed DNA methylation; RdDM), which facilitates transcriptional silencing of heterochromatin and transposable elements representing a large part of plant genomes. The presence of two RNA polymerases involved in this pathway is characteristic for flowering plants, which were discovered for the first time in the genome of Arabidopsis thaliana, which has also become the main plant model for the study of RdDM. Polymerase IV transcribes siRNA precursors; siRNAs are subsequently associated with AGO4 proteins and guide methylation enzymes to the target sequences via complementarity with polymerase V transcripts.
|
|
|
Role paternálního H4K12ac při utváření pronukleí a v časné embryogenezi u myší.
Dudková, Barbora ; Hortová, Kateřina (advisor) ; Stopka, Tomáš (referee)
During the process of spermatogenesis, histones are replaced by protamines, basic proteins enabling transmission of DNA to the oocyte during fertilization. In mouse sperm, there is only 1% of remaining histones whose N-terminal tails contain post-translationally modified residues. In this study, I was interested in contribution of paternal histone H4 acetylated on lysine K12 residues (H4K12ac) that is present in mature sperm head in remaining nucleosomes. Physiologically, H4K12ac has an important role in transcription factor accumulation and in regulation of gene expression. The presence and abundance of H4K12ac modification in various pronuclei stages of 1-cell embryo and parthenotes were assessed by imunnoflourescent detection with utilization of anti-H4K12ac antibody. Altogether, the paternal pronucleus exhibits a strong acetylation signal on H4K12 since its formation, while in the maternal one, there is a slow continual increase of H4K12ac getting on the same level as paternal pronucleus till the pronuclei fusion. Simultaneously DNA methylation status in both pronuclei was detected. In paternal pronucleus there is a continual decrease in the DNA methylation detectable as a decrease of 5mC and an increase of 5hmC signal. Meanwhile, the maternal pronucleus stays widely methylated. DNA...
|
|
|
Epigenetic regulation of HLA class II genes and their role in autoimmune diseases.
Čepek, Pavel ; Kotrbová - Kozak, Anna Katarzyna (advisor) ; Horníková, Lenka (referee)
Abstract Background: Type 1 diabetes (T1D) is a multifactorial autoimmune disease. Its incidence in Europe is continuously rising. The highest T1D risk is associated with HLA (human leukocyte antigen) class II genes. HLA class II molecules play a key role in regulation of immune response. They contribute to the selection of T cell repertoire by presenting antigenic peptides to the CD4+ T lymphocytes. HLA class II expression is controlled by regulatory module that is situated 150 - 300 base pairs upstream of the transcription- initiation site in all HLA class II genes. Polymorphisms in this region are linked to some autoimmune diseases. There were identified several promoter alleles (named QAP) in the HLA DQA1 gene promoter region. Most of the polymorphisms appear to be conserved within haplotype. Individual QAP alleles may have a different promoter strength by which they influence expression of HLA DQA1 gene alleles. Promoter strength can be modulated by DNA methylation. Aims:Our aim was to define methylation profile of HLA DQA1 promoters and determine the mRNA expression of individual alleles of HLA DQA1 gene in T1D patients. The mRNA expression level of HLA DQA1 gene alleles was determined using quantitative PCR. Methods: 30 diabetic pacients (age range 21 to 76 years), were included in this pilot...
|
guest ::
