Differences between the endogenous and exogenous dna sequences of rous-associated virus-O

Humphries, E H; Glover, Caroline; Weiss, Robin A.; Arrand, John R.

doi:10.1016/0092-8674(79)90133-8

Cited by 29 publications

(29 citation statements)

References 46 publications

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“…Such methylation has been shown to be characteristic of non-transcribed regions of DNA Vardimon et al, 1980;Desrosiers et al, 1979;van der Ploeg & Flavell, 1980). Cells containing only endogenous proviruses of Rous-associated virus (RAV) (Humphries et al, 1979) or mouse mammary tumour virus (MMTV) (Cohen, 1980) have no unmethylated viral sequences. When these cells become infected, begin producing virus and acquire exogenous proviruses, they acquire unmethylated viral sequences.…”

Section: Cis-acting Control Of Provirus Expressionmentioning

confidence: 99%

Regulation of Expression of the Integrated Retrovirus Genome

Weinberg

Steffen²

1981

Journal of General Virology

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Section: Cis-acting Control Of Provirus Expressionmentioning

confidence: 99%

Regulation of Expression of the Integrated Retrovirus Genome

Weinberg

Steffen²

1981

Journal of General Virology

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“…PR-RSV-A DNA intermediates were prepared by exposing C/E CEF to PR-RSV-A for 3 consecutive hr at a multiplicity ofapproximately 3-4; the inoculum was changed each hour. Thirty-six hours after infection, the cells were used to prepare linear PR-RSV-A DNA as described (12 Gel slices (1.5 mm) were dialyzed twice at 25YC for 15 minperiods against 1 ml of 10 mM Tris HCl, 7.5/10 mM MgCl2. The slices were pooled into three fractions: 0-0.6 mm, 0.6-1.2 mm, and 1.2-1.8 mm.…”

mentioning

confidence: 99%

“…DNA Purification. High molecular weight DNA was purified from cells as described (12). PR-RSV-A DNA intermediates were prepared by exposing C/E CEF to PR-RSV-A for 3 consecutive hr at a multiplicity ofapproximately 3-4; the inoculum was changed each hour.…”

mentioning

confidence: 99%

Rous sarcoma virus infection of synchronized cells establishes provirus integration during S-phase DNA synthesis prior to cellular division.

Humphries¹,

Glover²,

Reichmann³

1981

Proc. Natl. Acad. Sci. U.S.A.

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Synchronized chicken embryo fibroblasts, prepared by addition of serum to stationary cells arrested in G., were exposed to the Prague strain of Rous sarcoma virus. At different times during the cell cycle, high molecular weight DNA was prepared from infected cells and examined for the presence of newly integrated viral DNA sequences. The results demonstrate that newly integrated viral sequences were first detected during Sphase DNA synthesis 9 hr after infection. The presence of colchicine prevented cellular division and delayed the appearance of progeny virus but it did not affect the appearance of viral specific DNA in the high molecular weight fraction of cellular DNA. Our results indicate that provirus integration, occuring during S-phase DNA synthesis, does not require cell division. Previous experiments have demonstrated that Rous sarcoma virus infection of chicken embryo fibroblasts requires cell division to initiate viral RNA synthesis and the production of progeny virus. The findings presented in this report support the hypothesis that division of the infected cell is required for an event that controls viral expression at the level of the integrated provirus.The replication of Rous sarcoma virus (RSV) proceeds through the formation and integration of a DNA copy of the viral genome, the provirus (1). Initiation oftranscription ofthe provirus and the production of infectious virus require an initial division of the newly infected cell (2, 3). However, when cells are arrested in Go after the production of progeny RSV has already begun, both the transcription of viral RNA and the production of virus continue in the absence of further cell division (3, 4). The requirement for cell division, therefore, is not continuous and appears to be an event necessary for activation of the provirus (5).Analysis of the early events in provirus formation has demonstrated that viral DNA synthesis is initiated after RSV infection of stationary cells (6). Examination of the viral DNA synthesized in these cells has revealed that it is incomplete and noninfectious (7). Complete synthesis of the provirus and its integration into cellular DNA has been shown to require an undefined host cell function(s) (8). To determine whether this host function(s) is related to the event(s) required for activation of the provirus, we analyzed the integration of the provirus in synchronized cells. The results presented below indicate that the complete provirus can be synthesized and integrated during S-phase DNA synthesis. Although the presence of colchicine inhibits the production of progeny virus, it has no effect on either the synthesis or integration of the provirus. It is likely, therefore, that the host function(s) required for the synthesis and integration of viral DNA is distinct from that required to activate the provirus. It seems that activation of the provirus depends on an event(s) that follows mitosis because colchicinetreated cells arrested in metaphase contain an inactive provirus.EXPERIMENTAL PROCEDURES Cells and Virus...

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“…We have previously reported hypermethylation of integrated avian retrovirus genomes in the non-permissive rat cell line, XC, while exogenously introduced genomes present in permissive chicken cells are not detectably methylated (Guntaka et al, 1980). In addition, as also shown by Humphries et al (1979), we have shown that endogenous virus sequences (RAV-O) present in normal chicken cells are also methylated (Guntaka et aL, 1980). Likewise, in the mov-3 substrain of mice, the integrated MMuLV provirus has been shown to be highly methylated whereas the same provirus cloned in bacteria is not methylated (Harbers et al, 1982).…”

Section: Discussionmentioning

confidence: 85%