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Host-virus interactions of mammalian endogenous retroviruses
Farkašová, Helena ; Elleder, Daniel (advisor) ; Hirsch, Ivan (referee) ; Mělková, Zora (referee)
Endogenous retroviruses (ERVs) originate by germline infection and subsequent mendelian inheritance of their exogenous counterparts. With notable exceptions, all mammalian ERVs are evolutionarily old and fixed in the population of its host species. Some groups of retroviruses were believed not to be able to form endogenous copies. We discovered an additional endogenous Lentivirus and a first endogenous Deltaretrovirus. Both of these groups were previously considered unable to form endogenous copies. Endogenous lentiviruses were discovered only recently and are still quite rare. These are still just small pieces of evidence insufficient to give a broader picture about the history of virus endogenization. We described a novel endogenous Lentivirus in the genome of Malayan colugo (Galeopterus variegatus) denoted ELVgv (endogenous Lentivirus of G. variegatus). Based on several analyses we proved that this is the oldest Lentivirus discovered up to date and confirmed its presence in the only other extant species of Dermoptera - Cynocephalus volans. Endogenous deltaretroviruses were the last group without a single endogenous member. We detected the remnants of endogenous Deltaretrovirus in the genome of Natal Long-fingered bat (Miniopterus natalensis). However, this sequence was present in the genome only in one...
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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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Host-virus interactions of mammalian endogenous retroviruses
Farkašová, Helena
Endogenous retroviruses (ERVs) originate by germline infection and subsequent mendelian inheritance of their exogenous counterparts. With notable exceptions, all mammalian ERVs are evolutionarily old and fixed in the population of its host species. Some groups of retroviruses were believed not to be able to form endogenous copies. We discovered an additional endogenous Lentivirus and a first endogenous Deltaretrovirus. Both of these groups were previously considered unable to form endogenous copies. Endogenous lentiviruses were discovered only recently and are still quite rare. These are still just small pieces of evidence insufficient to give a broader picture about the history of virus endogenization. We described a novel endogenous Lentivirus in the genome of Malayan colugo (Galeopterus variegatus) denoted ELVgv (endogenous Lentivirus of G. variegatus). Based on several analyses we proved that this is the oldest Lentivirus discovered up to date and confirmed its presence in the only other extant species of Dermoptera - Cynocephalus volans. Endogenous deltaretroviruses were the last group without a single endogenous member. We detected the remnants of endogenous Deltaretrovirus in the genome of Natal Long-fingered bat (Miniopterus natalensis). However, this sequence was present in the genome only in one...
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Host-virus interactions of mammalian endogenous retroviruses
Farkašová, Helena
Endogenous retroviruses (ERVs) originate by germline infection and subsequent mendelian inheritance of their exogenous counterparts. With notable exceptions, all mammalian ERVs are evolutionarily old and fixed in the population of its host species. Some groups of retroviruses were believed not to be able to form endogenous copies. We discovered an additional endogenous Lentivirus and a first endogenous Deltaretrovirus. Both of these groups were previously considered unable to form endogenous copies. Endogenous lentiviruses were discovered only recently and are still quite rare. These are still just small pieces of evidence insufficient to give a broader picture about the history of virus endogenization. We described a novel endogenous Lentivirus in the genome of Malayan colugo (Galeopterus variegatus) denoted ELVgv (endogenous Lentivirus of G. variegatus). Based on several analyses we proved that this is the oldest Lentivirus discovered up to date and confirmed its presence in the only other extant species of Dermoptera - Cynocephalus volans. Endogenous deltaretroviruses were the last group without a single endogenous member. We detected the remnants of endogenous Deltaretrovirus in the genome of Natal Long-fingered bat (Miniopterus natalensis). However, this sequence was present in the genome only in one...
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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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Host-virus interactions of mammalian endogenous retroviruses
Farkašová, Helena ; Elleder, Daniel (advisor) ; Hirsch, Ivan (referee) ; Mělková, Zora (referee)
Endogenous retroviruses (ERVs) originate by germline infection and subsequent mendelian inheritance of their exogenous counterparts. With notable exceptions, all mammalian ERVs are evolutionarily old and fixed in the population of its host species. Some groups of retroviruses were believed not to be able to form endogenous copies. We discovered an additional endogenous Lentivirus and a first endogenous Deltaretrovirus. Both of these groups were previously considered unable to form endogenous copies. Endogenous lentiviruses were discovered only recently and are still quite rare. These are still just small pieces of evidence insufficient to give a broader picture about the history of virus endogenization. We described a novel endogenous Lentivirus in the genome of Malayan colugo (Galeopterus variegatus) denoted ELVgv (endogenous Lentivirus of G. variegatus). Based on several analyses we proved that this is the oldest Lentivirus discovered up to date and confirmed its presence in the only other extant species of Dermoptera - Cynocephalus volans. Endogenous deltaretroviruses were the last group without a single endogenous member. We detected the remnants of endogenous Deltaretrovirus in the genome of Natal Long-fingered bat (Miniopterus natalensis). However, this sequence was present in the genome only in one...
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Epigenetic regulation of retroviruses.
Dobšová, Martina ; Trejbalová, Kateřina (advisor) ; Drda Morávková, Alena (referee)
The human genome is the site of integration of the retrovirus HIV-1, ERVWE1 (syncytin-1) is its stable part. Thus as an integral part of the genome, they are under influence of important genome based epigenetics regulations, such as DNA methylation, histone methylation and acetylation. Promoter DNA hypermethylation and histone deacetylation leads to establishment and maintenance of latent state of the HIV-1 virus and formation of the latent reservoir in the CD4+ memory T-cells. This process leads to severe problems during HIV-1 infection treatment by antiretroviral therapy (HAART), as the HIV-1 latent reservoir remains unaffected. Moreover DNA hypermethylation in the promoter of syncytin-1 directs its transcriptional silencing, which is important in tissue specific regulation of this fusogenic protein. In physiological conditions syncytin-1 expression is observed only in placental cells, where the DNA methylation of promoter is decreased. Higher expression level of syncytin-1 was also observed in several other tissues, such as testes, where it is tightly coupled with germ-cells tumors and syncytin-1 promoter hypomethylation. In conclusion, epigenetic regulation of retroviruses by DNA methylation and chromatin modifications highly influence regulation of their expression. Presented bachelor thesis...
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