National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
The role of somatic mutations in the pathogenesis of myelodysplastic syndrome
Minařík, Ľubomír ; Stopka, Tomáš (advisor) ; Žák, Pavel (referee) ; Beličková, Monika (referee)
9 Abstract: Myelodysplastic syndromes (MDS) are a set of severe hematological diseases characterized by ineffective clonal hematopoiesis in the bone marrow, leading to cytopenia in the peripheral blood, the development of transfusion dependence and a high risk of progression to acute myeloid leukemia (AML). The disease is caused by genetic and epigenetic changes leading to the development of pathological stem cells that are unable to mature sufficiently in the bone marrow into blood elements. These changes vary widely between patients, which is reflected in different clinical manifestations, response to treatment, overall survival and, last but not least, this heterogeneity represents a challenge for the study of this disease. The present dissertation is aimed at studying the pathophysiological manifestations and consequences of selected genetic alterations, especially somatic mutations of key genes and other functional units of the genome, in relation to the clinical course of MDS and transformation to AML. Therapy of high-risk MDS is currently based on hypomethylating drugs including 5- azacytidine (AZA). Treatment leads to prolongation of disease progression to AML, but this fate is irreversible for the vast majority of patients whose prognosis becomes hopeless at this point. Results of genetic analysis...
Identification and functional characterization of C/EBPalpha targets in normal and malignant hematopoiesis
Zjablovskaja, Polina ; Alberich Jorda, Meritxell (advisor) ; Stopka, Tomáš (referee) ; Fuchs, Ota (referee)
Thehematopoieticsystemisahighlyorganizedstructure, whichhastobetightly regulatedinordertofunctionproperly.Abnormalitiesinhematopoieticdevelopmentmaylead tohematologicaldisorders,suchasacutemyeloidleukemia(AML).Thefunctionalityofthe hematopoieticsystemlargelyreliesontranscriptionfactors.C/EBPtranscriptionfactoris knownasoneofthe majorhematopoieticregulators,requiredforthefunctionalityof hematopoieticstemcellsaswellasformyeloidlineagedevelopment.Importantly,C/EBP expressionisalteredinalargeproportionofAMLcases.C/EBPregulateshematopoiesis mainlythroughorchestratingexpressionofitstargetgenes.ManyoftheC/EBPtargetshave previouslybeenshowntoplayaroleinthehematopoieticsystemandtobeinvolvedin leukemictransformation. That makesidentificationofnovel C/EBP targetsandtheir functionalcharacterizationanexcitingsubjectofresearch.Hereweidentifiedalistofgenes whoseexpressiondependsontheactivityofC/EBPthesocalledC/EBPsignature. We demonstratedthattreatment withhistonedeacetylase(HDAC)inhibitorsreactivatesthe expressionofthesegenesincellswithnon-functionalC/EBP.Inaddition,wedemonstrated thattreatmentwiththeHDACinhibitorspromotesmyeloiddifferentiationinAMLsamples carryingbi-allelicCEBPA mutationsandcharacterizedbythereducedexpressionofthe...
SWI2/SNF2 ATPases with a focus on the ISWI subfamily: protein complexes and mouse models for their study
Turková, Tereza ; Stopka, Tomáš (advisor) ; Janoštiak, Radoslav (referee)
In the nucleus the DNA is packed along with proteins into a dynamic structure called chromatin. During cell cycle the chromatin structure becomes a subject to various changes. During interphase chromatin structure becomes loose while shortly before cell division it undertakes the form of highly condensed mitotic chromosomes. Structure of chromatin influences significantly mode of gene expression and its pattern. DNA-binding proteins interacting within chromatin are also necessary during this process. To gain the access to the DNA binding factors, the chromatin has to be in a loosened form. As long as the structure of the chromatin is more condensed it creates a barrier for the DNA binding proteins. Therefore it becomes obvious that the remodeling of the chromatin structure is one of the important regulators of gene expression and that the enzymes, which execute remodeling, are of great importance. One of them is ATPase Smarca5, which belongs to the protein subfamily ISWI and which creates the catalytic subunit for several different ATP-dependent chromatin remodeling complexes. Mutations of members of those complexes disturb regulation of transcription and cellular differentiation. In some cases the incorrect function of these complexes can lead to cellular transformation into a tumours state. This...
Regulatory mechanisms in normal and malignant granulopoiesis
Kardošová, Miroslava ; Alberich Jorda, Meritxell (advisor) ; Stopka, Tomáš (referee) ; Balounová, Jana (referee)
Neutrophils, known primarily as key players in defense against invading pathogens, represent an essential component of both the innate and adaptive immunity. Continuous production of large quantities of neutrophils is ensured by a complex process termed granulopoiesis. In order to maintain a stable neutrophilic population, granulopoiesis requires to be tightly regulated. Moreover, impaired granulopoiesis may lead to aberrant bone marrow function and, ultimately, give rise to acute myeloid leukemia (AML). Despite decades of research, the mechanisms regulating granulopoiesis are still unclear. In particular, the CCAAT/enhancer binding protein (C/EBP) family of transcription factors plays a critical role in this process. C/EBPα acts as a master regulator of granulopoiesis mainly by orchestrating expression of its target genes, which will mediate granulocytic differentiation. Thus, characterization of novel C/EBPα target genes is critical for a better understanding of the molecular mechanisms that regulate granulopoiesis. Previously, we showed that another C/EBP member, CEBPG, is a direct target of C/EBPα. In the first part of the present work, we addressed the unknown role of C/EBPγ in granulopoiesis. We observed that Cebpg conditional knockout (KO) mice, which have the Cebpg gene ablated specifically...
The role of microRNAs in lymphomas with a focus on miR-155
Hušková, Hana ; Stopka, Tomáš (advisor) ; Svoboda, Petr (referee)
MicroRNAs (miRNAs) are 19-25 nucleotide noncoding RNAs which regulate the expression of target mRNAs at both posttranscriptional and translational level. The physiological functions of miRNAs include development, differentiation, cell cycle regulation and apoptosis. miRNA deregulation has been found in various human diseases, including lymphoproliferative disorders. This Bachelor thesis provides introduction to delineate roles of miRNAs in normal hematopoiesis and cites recent publications on miRNAs in lymphomas with a focus on the role of miR-155. Key words microRNA, hematopoiesis, lymphoma, miR-155
Transcriptional regulation of miR-17-92 microRNA cluster during macrophage differentiation.
Rybářová, Jana ; Stopka, Tomáš (advisor) ; Pospíšek, Martin (referee)
miR-17-92 cluster (Oncomir1) encodes seven microRNAs (miRNA, miR) regulating many biological processes including proliferation, differentiation or apoptosis. Overexpression of microRNAs encoded by miR-17-92 cluster is found in a number of tumors including acute and chronic myeloid leukemias (Dixon-McIver et al., 2008; Li et al., 2008; Venturini et al., 2007). Myeloid progenitors express miR-17-92 cluster at a high level, while macrophage differentiation associates with its downregulation. Our laboratory found, that miR-17-92 cluster is repressed by transcription factor Early growth response 2 (Egr2) upon differentiation of primary myeloid PUER progenitors, induced with transcription factor PU.1. Aim of this thesis is to further test the abovementioned data by preparing a reporter vectors set, carrying various fragments of miR-17-92 putative promoter, which enables us to study regulation of transcription of miR-17-92 cluster. This task complicated by presence of increased GC content of the miR-17-92 promoter was successfully accomplished resulting in amplification of eight fragments containing the various parts of miR-17-92 promoter including region -3.3 to 0 kb relative to the start of miR-17-5p sequence, that were inserted into pGL3 reporter vector. Transfection of pGL3 reporter vector carrying...
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...
Role of Smarca5 (Snf2h) during transcription of transfected DNA template.
Zikmund, Tomáš ; Stopka, Tomáš (advisor) ; Smetana, Karel (referee)
Cellular and tissue characteristics are results of dynamic regulation of gene expression. DNA wrapped into proteins, referred to as chromatin, requires involvement of mechanisms guiding accessibility of specific sequences. In higher organisms, chromatin remodeling proteins are indispensable in regulating chromatin structure including ISWI ATPase SMARCA5. SMARCA5 is involved in almost any transaction on DNA including transcription, however precise in vivo role of SMARCA5 in these processes remains unknown. To advance understanding of specific role of SMARCA5 in the development of chromatin structure during transcription we devised cellular model in which SMARAC5 level is manipulated while chromatin structure development and transcriptional response are monitored. Our data indicate that the transfected DNA template that is transcribed is enriched with histone H3 and its specific methylation of Histone H3 lysine (K) 4, a mark of active chromatin structure. Overexpression of SMARCA5 results within the reporter gene coding sequence in ~2,5-3 fold increase of both H3 occupancy an its modification H3K4Me3. Increased DNA template commitment into chromatinization is associated with repression of reporter gene expression. These results are supported by studies indicating dynamic development of nucleosomal...
Targeted therapy of AML1-ETO positive acute myeloid leukemia with histone deacetylase inhibitors
Zápotocký, Michal ; Trka, Jan (advisor) ; Stopka, Tomáš (referee) ; Trbušek, Martin (referee)
In t(8;21) acute myeloid leukaemia (AML), the leukemogenesis is supposed to be promoted by interference with expression of AML1 target genes. Repressor complex associated with AML1-ETO fusion protein recruits class I histone deacetylases (HDAC). Valproic acid (VPA) was found to have an extensive effect on AML blasts, via inhibition of class I HDAC. We aimed to characterize the differentiation effect of VPA on AML1-ETO-positive leukemic cells and to determine the expression pattern of AML1 target genes. Kasumi-1 (M2 AML1-ETO-positive), Kasumi-6 (M2 AML1-ETO- negative), MV4-11 (MLL-AF4-positive) and K562 cells were treated with VPA and 12-0-tetra- decanoylphorbol-13-acetate (TPA) and examined by flow cytometry and qRT-PCR. Two AML1-ETO- positive and two negative patients' bone marrow diagnostic samples were treated with VPA and TPA to confirm in vitro findings. Valproic acid induced apoptosis in AML1-ETO-positive and MLL- AF4-positive cells in dose dependent manner. But changes of immunophenotype proving the differentiation were observed purely in AML1-ETO-positive cell line (decreased CD33/34/117 and increased CD11a/11b expression). However, differentiated cells exhibited positivity of AnnexinV; hence the relationship between cell death and differentiation had to be evaluated. Apoptosis was blocked by...
Production and analysis of cellular conditional inactivation models of the ISWI ATPase Smarca5
Tauchmanová, Petra ; Stopka, Tomáš (advisor) ; Burda, Pavel (referee)
The eukaryotic nuclear processes such as replication, DNA damage repair (DDR) and transcription are highly dependent on the regulation of chromatin structure. The dynamic changes in chromatin accessibility are controlled by a class of chromatin-remodeling factors which form multimeric complexes and use ATP as the source of their helicase activity. In this study we have established a mouse embryonic fibroblast in vitro model with conditional inactivation of chromatin remodeling ATPase Smarca5 and used this powerful tool to test the regulation of cell cycle, proliferation and DDR signaling in conditions with low Smarca5 activity. Our results show that decreased dosages lead to decreased proliferation apparent already within few days post induction of Smarca5 deletion that is accompanied with decrease of cells in S and M phases of cell cycle, increasing cell ploidy and accelerated cell senescence. Additionally, the Smarca5 depleted cells upregulated many protein markers associated with DNA damage and cellular stress. Our results thus indicate that Smarca5 has indispensable roles during cell proliferation including in the maintenance of genome integrity during S phase of cell cycle.

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