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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...
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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...
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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...
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