National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
In vitro models for studying Syncytin-1-induced fusion of trophoblast cells
Jech, Lukáš ; Trejbalová, Kateřina (advisor) ; Zíková, Martina (referee)
Trophoblast cell fusion is essential for human placenta development. Apart from initiating blastocyst implantation, syncytialization is critical for optimal nutrient and gas exchange between mother and fo- etus. Multicellular syncytia called syncytiotrophoblast covers the surface of the branched structure of chorionic villi, which is in direct contact with maternal blood. Impairment of the syncytialization process leads to insufficient fetal nutrition and severe pregnancy complications. Syncytia formation is induced by the interaction of the surface glycoprotein of retrovital origin, Syncytin-1, with its receptor. Despite the significance of these processes, the details of cell fusion and trophoblast differentiation remain unk- nown. Furthermore, because of its uniqueness, the human placenta cannot be covered by animal models. As a result, research into human placental development, especially Syncytin-1-induced trophoblast cell fusion, is limited to in vitro trophoblast models. These models include primary trophoblast cell cultures and trophoblast cell lines, which can be obtained by immortalizing cell cultures or extracted from trophoblast tumours. Dedifferentiated trophoblast stem cell cultures were also established. The most recent approach, however, involves the direct reprogramming of dermal...
Polyomavirus minichromosomes: interactions with components of innate imunity
Satratzemis, Christos ; Forstová, Jitka (advisor) ; Trejbalová, Kateřina (referee)
The genome of polyomaviruses is a circular dsDNA (double-stranded DNA) which is associated with cellular histones within virions and during the entire viral replication cycle. Given the structural similarity to eukaryotic chromatin, the complex of polyomaviral DNA with histones is called minichromosome. The chromatin state of minichromosomes influences viral transcription and replication which could be exploited by the host innate immune response. One of the components of innate immunity, that affects viral chromatin, is the non-canonical histone H3.3, its chaperone DAXX- ATRX (death domain associated protein 6-alpha-thalassemia, mental retardation X-linked syndrome) and protein complexes called PML (promyelocytic leukemia protein). In order to trigger the innate immune response, foreign and/or stress molecules have to detected. During mouse polyomavirus (MPyV) infection, the innate immune response is initiated via the DNA sensor cGAS (cyclic GMP- AMP synthase). In this master's thesis, the distribution of histone H3.3, its chaperone DAXX-ATRX and the PML protein was analyzed during infection with MPyV. Using mass spectrometry, the histone was detected within viral chromatin. The data suggest that the chaperone complex and PML are involved in the regulation of H3.3 incorporation into the chromatin...
Regulation of alternative splicing
Dušková, Eva ; Staněk, David (advisor) ; Trejbalová, Kateřina (referee)
Alternative splicing is an important cellular mechanism. It allows to produce multiple protein isoforms from a limited number of genes. Regulation of alternative splicing involves cis-acting elements on pre-mRNA and trans-acting splicing factors (SR and hnRNP proteins). Because splicing occurs co-transcriptionaly, chromatin structure appears to have a role in the regulation of alternative splicing. We have studied the effect of histone acetylation on alternative splicing. We have prepared splicing reporter for alternative EDB exon, which is part of the fibronectin gene. We have shown, that the inhibition of histone deacetylases affects splicing pattern of EDB exon from the reporter in the same way as the splicing of the endogenous EDB exon. Furthermore, we have shown, that the structure of the promoter affects splicing of alternative EDB exon from splicing reporter. Currently we have found out, that the structure of the promoter influences the degree of histone H4 acetylation. Inclusion of alternative EDB exon in mRNA was inversely proportional to histon acetylation on the reporter. This work might explain why various promoters have different splicing patterns of alternative exons.
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...
Effects of heme metabolism on HIV-1 latency reversal
Kompas, Maroš ; Mělková, Zora (advisor) ; Trejbalová, Kateřina (referee)
Progression of HIV infection in HIV-positive patients can now be successfully controlled by the combined antiretroviral therapy. However, due to persistence of the latent reservoir, HIV infection cannot be cured. The immune system nor current therapeutic approaches can target the pool of latently infected cells, thus strategies aiming at reactivation and subsequent elimination of the reservoir cells are recognized as possibly curative. This thesis has examined previously demonstrated latency-reversing capacity of heme arginate (HA), another redox modulator, and their synergism with Protein Kinase C inducer phorbol myristate acetate (PMA) to reactivate HIV-1 in the context of heme metabolism. HIV-1 reactivation was assessed by the intensity of green fluorescence in the model Jurkat cell line clone (A2), containing HIV-1 "mini-virus" (LTR-Tat-IRES-EFGP-LTR), as well as in the A2 cells stably transfected with plasmid vectors encoding cDNA for specific factors of heme metabolism and for control luciferase. While the administration of redox modulator alone did not stimulate expression from the HIV-1 LTR and HA reactivated the "mini-virus" only slightly, both compounds revealed a synergy with PMA in all cell lines studied. Basal and induced expression of EGFP was found variable in cells transfected with...
Determinants of fusogenicity of Syncytin-1, cellular glycoprotein of retroviral origin
Trávníček, Martin ; Trejbalová, Kateřina (advisor) ; Zábranská, Helena (referee)
Syncytin-1 is an endogenous retroviral envelope glycoprotein specifically expressed in human placenta, where the protein was adopted for its physiological function. After interaction with specific receptors, transmembrane proteins ASCT1 and ASCT2, Syncytin-1 initiates cell-cell fusion leading to formation of multinucleated syncytiotrophoblast, which is essential for feto-maternal nutrients exchange. In this diploma thesis a new cell-cell fusion quantification assay was implemented for characterisation of Syncytin-1 fusion determinants. The assay uses Syncytin-1 and ASCT2 expressed separately with fragments of luciferase in heterologous cell-culture system. The assay enables to specifically quantify cell-cell fusions based on activity of reconstituted luciferase reporter. This study discovered new facts about the role of intracytoplasmic tail of Syncytin-1 in the process of the cell- cell fusion. This specific part of protein contains a tandem motif sensitive to changes in amino acid sequence that led to loss of fusogenic potential of Syncytin-1. It was further confirmed, that the protein Suppressyn works as an inhibitor of cell-cell fusions initiated by Syncytin-1. Suppressyn however does not bind to receptors of Syncytin-1 and the mechanism of its inhibition remains unsolved. Finally, it was demonstrated...
TET1 overexpression, DNA hypomethylation and aberrant expression of human endogenous retrovirus ERVWE1 in germ cell tumors
Benešová, Martina ; Trejbalová, Kateřina (advisor) ; Černá, Marie (referee) ; Reiniš, Milan (referee)
TGCTs are tumors of male germ cells. They comprise of seminomas and non-seminomas (embryonal carcinoma, yolk sac tumor, choriocarcinoma, and teratoma). GCT types differ in the stage of differentiation, from undifferentiated seminoma to more differentiated non-seminomas. In our studies, we aimed to characterize specific epigenetic features of GCT types that enable transcription derepression of the human endogenous retrovirus ERVWE1 in these tumors. We detected upregulated mRNA expression of TET1-3 dioxygenases in GCTs, especially of TET1 in seminomas. Moreover, seminomas showed low global levels of 5mC and 5hmC. TET1 knock-down in a seminoma-derived cell line resulted in a decreased amount of 5hmC and unchanged 5mC level. These results stress the dynamics of cytosine modifications, which has not been precisely described yet. Further, we observed high level of ERVWE1 transcript together with efficient RNA splicing in seminomas. Detected ERVWE1 transcription is independent of the expression of other examined endogenous retroviruses. ERVWE1 transcription derepression corresponds with the low global level of 5mC detected in seminomas, which involves extensive DNA hypomethylation of the ERVWE1 promoter. We propose the high TET1 dioxygenase expression as s marker of undifferentiated GCTs. Furthermore, we...
Gradual Molecular Changes in Primary Porcine Cells Expressing Mutated Huntingtin
Šmatlíková, Petra ; Motlík, Jan (advisor) ; Trejbalová, Kateřina (referee) ; Reiniš, Milan (referee)
Huntington's disease (HD) is inherited fatal disorder caused by CAG triplet expansions in the huntingtin gene resulting in the expression of mutated huntingtin protein (mtHtt). The main symptoms of HD are neurodegeneration, osteoporosis, testicular degeneration, loss of muscle tissue and heart muscle malfunction, weight loss, metabolic changes, and sleeping disturbances. Since huntingtin protein (Htt) has a role in several biological processes, many molecular mechanisms, like oxidative stress, mitochondrial dysfunction, DNA-damage, and others, are affected by mtHtt. However, its exact pathogenic mechanisms in HD are still not well understood. Transgenic minipig model of HD (TgHD) serves an opportunity to isolate unlimited number of primary cells and unlike primary cells obtained from HD patients, often in the late stages of the disease, the TgHD minipig model allows to monitor molecular changes occurring gradually with age and progression of the disease. Thus, TgHD minipig model and primary cells isolated from it play an important role in investigating and understanding the underlying mechanistic cause of HD. We focused on molecular and cellular changes in primary cells isolated from TgHD minipigs and their wild type (WT) controls at different ages (24, 36, and 48 months). In mesenchymal stem cells...
Interaction of transmembrane proteins ASCT1 and ASCT2 with retroviral envelope glycoproteins
Trávníček, Martin ; Trejbalová, Kateřina (advisor) ; Mělková, Zora (referee)
Transmembrane proteins ASCT1 and ASCT2 are ubiquitous neutral amino acid transporters. Apart from their transporter function in metabolically active cells, they also serve as receptors for a wide group of retroviruses. All retroviruses recognizing the transmembrane receptor ASCT2/ASCT1 share a similar env gene, encoding the envelope glycoprotein. Syncytin-1 is the envelope glycoprotein, encoded by human endogenous retrovirus type W, produced in placental cytotrophoblasts of primates, including human. Interaction of receptor binding domain of Syncytin-1 and specific extracellular region of ASCT2 is responsible for fusion of neighbouring cells and formation of multinucleated syncytiotrophoblast. The importance of syncytiotrophoblast lies in higher efficiency of feto-maternal exchange of nutrients and simultaneously in modulation of immune response of mother towards fetus. Defect in syncytiotrophoblast differentiation often leads to complications during pregnancy and impairs the proper development of embryo. Characterization of protein domains responsible for the interaction between Syncytin-1 and its receptors is important to uncover genetic causes of these pathologies. Furthermore, understanding the interaction helps us to clarify the mechanism of cell entry and explains the molecular basis of host...
Changes of the intracellular redox state during virus infections
Kompas, Maroš ; Mělková, Zora (advisor) ; Trejbalová, Kateřina (referee)
Viruses are infectious agens, which cause disruption of a host cellular redox homeostasis. This effect is mediated by cellular defense machinery or via viral gene products. In order to restore cellular redox enviroment, activation of cellular adaptive response takes place. That is mediated by transcription factor Nrf2, which leads to upregulation of gene expression of antioxidant enzymes. Under suboptimal redox condition, or by detecting foreign nucleic acid, redox sensitive transcription factor Nf-κB is also being activated, what leads to expresion of proteins mediating cellular imunne responses. It is important to remember that these proteins might show malignant effects to surrounding tissues during long term inflammations. With respect to that, viruses have evolved mechanisms, through which they are able to overcome or hijack these pathways, in order to propagate the infection. Key words: intracellular redox state, ROS, RNS, oxidative stress, antioxidant enzymes, regulation of gene expression, virus infections

National Repository of Grey Literature : 15 records found   1 - 10next  jump to record:
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1 Trejbalová, Karolína
1 Trejbalová, Katarína
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