The second large simian virus 40 T-antigen exon contains the information for maximal cell transformation

Graessmann, M.; Guhl, Eva; Bumke-Vogt, Christiane; Graessmann, A.

doi:10.1016/0022-2836(84)90433-9

Cited by 12 publications

(3 citation statements)

References 39 publications

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“…This procedure allows identification and isolation of the recipient cells at any time after DNA transfer (3). SV40-transformed REF 52 cells were obtained after microinjection of SV40 DNA or SV40 DNA fragments as described in detail elsewhere (8). For anchorage-independent growth, cells were seeded into 0.33% Sea-Plaque agarose (FMC Corp., Marine Colloids Div.).…”

Section: Methodsmentioning

confidence: 99%

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Cellular mutation mediates T-antigen-positive revertant cells resistant to simian virus 40 transformation but not to retransformation by polyomavirus and adenovirus type 2

Bauer¹,

Guhl²,

Graessmann³

et al. 1987

J Virol

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T-antigen-positive transformation revertant cell lines were isolated from fully simian virus 40 (SV40)transformed Fisher rat embryo fibroblast cells (REF 52 cells) by methionine starvation. Reversion of the transformed cells (SV-52 cells) was caused by a mutation within the cellular genome. To demonstrate this, we isolated SV40 DNA from the host genome, inserted it into plasmid pSPT18 DNA, cloned it in Escherichia coli, and microinjected it into the nuclei of the REF 52 cells. Fully transformed cells were obtained with the same * Corresponding author. NaCl, 5 mM EDTA, 50 mM Tris hydrochloride [pH 7.4], 0.05% Nonidet P-40, 0.02% [wt/vol] NaN3) with 0.2%

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Section: Methodsmentioning

confidence: 99%

“…As a size marker, lambda DNA digested with EcoRI was used. The SV40 DNA-containing region (identified with a control gel and a DNA blot) was cut out and eluted from the gel as described previously (8). The isolated DNA was inserted into the EcoRI site of the pSPT18 plasmid vector (Pharmacia, Inc.) and propagated in Escherichia coli BHB2603.…”

Section: Methodsmentioning

confidence: 99%

Cellular mutation mediates T-antigen-positive revertant cells resistant to simian virus 40 transformation but not to retransformation by polyomavirus and adenovirus type 2

Bauer¹,

Guhl²,

Graessmann³

et al. 1987

J Virol

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“…The early phase is devoted to subversion of cellular control mechanisms to prepare the cell for the late phase. T antigen is an autoregulated phosphoprotein that accumulates in the nucleus during the early phase of infection; it alters cellular transcription patterns (6,43) and stimulates cellular DNA synthesis in quiescent cells (11,19,20,21,30,45). Upon transition to the late phase, T antigen sustains viral DNA replication and stimulates late gene expression and virion production.…”

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confidence: 99%

Simian virus 40 small-t antigen stimulates viral DNA replication in permissive monkey cells

Cicala¹,

Avantaggiati²,

Graessmann³

et al. 1994

J Virol

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The simian virus 40 (SV40) large-T antigen is essential for SV40 DNA replication and for late viral gene expression, but the role of the SV40 small-t antigen in these processes is still unclear. We have previously demonstrated that small t inhibits SV40 DNA replication in vitro. In this study, we investigated the effect of small t on SV40 replication in cultured cells. CV1 monkey cell infection experiments indicated that mutant viruses that lack small t replicate less efficiently than the wild-type virus. We next microinjected CV1 cells with SV40 DNA with and without purified small-t protein and analyzed viral DNA replication efficiency by Southern blotting. Replication of either wild-type SV40 or small-t deletion mutant DNA was increased three- to fivefold in cells coinjected with purified small t. Thus, in contrast to our in vitro observation, small t stimulated viral DNA replication in vivo. This result suggests that small t has cellular effects that are not detectable in a reconstituted in vitro replication system. We also found that small t stimulated progression of permissive monkey cells--but not of nonpermissive rodent cells--from G0-G1 to the S phase of the cell cycle, possibly leading to an optimal intracellular environment for viral replication.

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Experimental evidence for RNA trans-splicing in mammalian cells.

Eul

Graessmann

1995

The EMBO Journal

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We present evidence that mammalian cells have the ability to generate functional mRNA molecules by trans‐splicing. Rat cells, transformed by an early SV40 DNA fragment (Bst/Bam) synthesize a truncated T antigen (T1 antigen), although the cells do not have a direct sequence homology for the T1 antigen at the DNA level. The Bst/Bam DNA fragment encodes exclusively for the second SV40 T antigen exon (aa 83‐708) and contains the entire small t antigen intron. To synthesize the corresponding mRNA (T1 mRNA), the cells utilize a cryptic 5′ splice site within the second exon (codons for aa 131/132) as donor site and the upstream small t antigen 3′ splice site as the acceptor site. Since these sites are in an inverted order on the pre‐mRNA, two Bst/Bam transcripts are required to generate one T1 mRNA molecule. HeLa cell nuclear extracts also performed the trans‐splicing reaction in vitro.

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The second large simian virus 40 T-antigen exon contains the information for maximal cell transformation

Cited by 12 publications

References 39 publications

Cellular mutation mediates T-antigen-positive revertant cells resistant to simian virus 40 transformation but not to retransformation by polyomavirus and adenovirus type 2

Cellular mutation mediates T-antigen-positive revertant cells resistant to simian virus 40 transformation but not to retransformation by polyomavirus and adenovirus type 2

Simian virus 40 small-t antigen stimulates viral DNA replication in permissive monkey cells

Experimental evidence for RNA trans-splicing in mammalian cells.

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