It has now been more than two years since we said our last goodbye to Jan Svoboda (14 [...].

• MeSH
• lidé MeSH
• Retroviridae klasifikace   genetika   izolace a purifikace   fyziologie   MeSH
• retrovirové infekce virologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• úvodní články MeSH
• úvodníky MeSH

Most retroviruses preferentially integrate into certain genomic locations and, as a result, their genome-wide integration patterns are non-random. We investigate the epigenetic landscape of integrated retroviral vectors and correlate it with the long-term stability of proviral transcription. Retroviral vectors derived from the avian sarcoma/leukosis virus expressing the GFP reporter were used to transduce the human myeloid lymphoblastoma cell line K562. Because of efficient silencing of avian retrovirus in mammalian cells, only ∼3% of established clones displayed stable proviral expression. We analyzed the vector integration sites in non-selected cells and in clones selected for the GFP expression. This selection led to overrepresentation of proviruses integrated in active transcription units, with particular accumulation in promoter-proximal areas. In parallel, we investigated the integration of vectors equipped with an anti-silencing CpG island core sequence. Such modification increased the frequency of stably expressing proviruses by one order. The modified vectors are also overrepresented in active transcription units, but stably expressed in distal parts of transcriptional units further away from promoters with marked accumulation in enhancers. These results suggest that integrated retroviruses subject to gradual epigenetic silencing during long-term cultivation. Among most genomic compartments, however, active promoters and enhancers protect the adjacent retroviruses from transcriptional silencing.

• MeSH
• Alpharetrovirus genetika   MeSH
• buněčné linie MeSH
• buňky K562 MeSH
• CpG ostrůvky genetika   MeSH
• epigeneze genetická MeSH
• genetická transkripce * MeSH
• genetické vektory genetika   MeSH
• integrace viru genetika   MeSH
• lidé MeSH
• promotorové oblasti (genetika) genetika   MeSH
• proviry genetika   MeSH
• umlčování genů MeSH
• zesilovače transkripce genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

This article summarizes the essential steps in understanding the chicken Rous sarcoma virus (RSV) genome association with a nonpermissive rodent host cell genome. This insight was made possible by in-depth study of RSV-transformed rat XC cells, which were called virogenic because they indefinitely carry virus genetic information in the absence of any infectious virus production. However, the virus was rescued by association of XC cells with chicken fibroblasts, allowing cell fusion between both partners. This and additional studies led to the interpretation that the RSV genome gets integrated into the host cell genome as a provirus. Study of additional rodent virogenic cell lines provided evidence that the transcript of oncogene v-src can be transmitted to other retroviruses and produce cell transformation by itself. As discussed in the text, two main questions related to nonpermissiveness to retrovirus infection remain to be solved. The first is changes in the retrovirus envelope gene allowing virus entry into a nonpermissive cell. The second is the nature of the permissive cell functions required by the nonpermissive cell to ensure infectious virus production. Both lines of investigation are being pursued.

• Klíčová slova
• cell transformation, nonpermissiveness to virus infection, virus integration, virus rescue,
• MeSH
• buněčné linie MeSH
• fúze buněk * MeSH
• genom virový genetika   MeSH
• genové produkty env genetika   MeSH
• krysa rodu Rattus MeSH
• kur domácí virologie   MeSH
• onkogenní protein pp60(v-src) genetika   MeSH
• proviry genetika   růst a vývoj   MeSH
• virová transformace buněk MeSH
• virus Rousova sarkomu genetika   růst a vývoj   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• genové produkty env MeSH
• onkogenní protein pp60(v-src) MeSH