Simian virus 40 small-t protein is required for loss of actin cable networks in rat cells

Graessmann, A.; Graessmann, M.; Tjian, Robert; Topp, William C.

doi:10.1128/jvi.33.3.1182-1191.1980

Cited by 75 publications

(18 citation statements)

References 36 publications

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“…This 92-kilodalton phosphoprotein is a pleiotropic effector with numerous biochemical and biological functions. To name only a few, the SV40 T antigen is a DNA-binding protein with an inherent ATPase and an associated protein kinase activity, it stimulates cellular and viral DNA replication, it induces enhanced production of cellular proteins, such as the p53 tumor antigen, and it causes alterations in cell morphology and growth characteristics (6,16,19,20,22,26).…”

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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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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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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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“…SV40 t-antigen is necessary for efficient transfornation of growth-restricted cells (1,9,16); polyoma hr-t mutants that lack both small t-and middle T-antigens are almost totally transformation defective (18). A role for these gene products in disorganization of actin cable structure has been defined by microinjection experiments, for both polyoma virus (13) and SV40 (4). An intriguing possibility is that the cellular 56K and 32K proteins play some role in actin cable structure and that the interaction of the cellular proteins with t-antigens may explain the loss of organized cable structure in infected cells.…”

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confidence: 99%

Association of cellular 56,000- and 32,000-molecular-weight protein with BK virus and polyoma virus t-antigens

Rundell¹,

Major²,

Lampert³

1981

J Virol

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Two cellular proteins (molecular weights: 56,000 and 32,000) were specifically co-immunoprecipitated by simian virus 40 and BK virus t-antigens and by polyoma virus non-T early proteins.In a previous study (20), we demonstrated that two cellular proteins with apparent molecular weights of 56,000 (56K) and 32K were specifically iunmunoprecipitated in association with the simian virus 40 (SV40) t-antigen. The 56K and 32K proteins were found in infected and in uninfected cells. To demonstrate the presence of the proteins in uninfected cells, extracts of radiolabeled uninfected cells were mixed with unlabeled extracts of SV40-infected cells before immunoprecipitation. The specificity of the interaction was shown by the use of SV40 deletion mutants that do not synthesize intact small tantigen and by the use of specific antisera (10). The 56K and 32K proteins were not present in immunoprecipitates of cells infected with t-antigen deletion mutants or when antisera that do not recognize the viral t-antigen were used for immunoprecipitation.Other transforming papovaviruses code for the synthesis of t-antigens that resemble the SV40 t-antigen both in size and in sequences of cysteine-rich regions of the proteins (2, 3, 17). Consequently, it was of interest to determine whether t-antigens of the human papovavirus BK virus (BKV) and the mouse virus polyoma could promote the co-immunoprecipitation of cellular proteins from infected cells.Immunoprecipitation of proteins from BKVinfected cells was studied by using human embryonic kidney (HEK) cells that had been infected with wild-type BKV for 72 h at 37°C (8,19). The infected cells were pulsed with [35S]methionine for 24 h, then extracted with 0.5% Nonidet P-40 in Tris-buffered saline, pH 8. Extraction buffers included 2 to 5 mM dithiothreitol. Immunoprecipitation was done according to standard procedures (20). Proteins were immunoprecipitated by using antisera from hamsters bearing tumors of the SV40-transformed cell line, THE-2 (10). The SV40 and BKV large Tand small t-antigens cross-react immunologically (11,15), and the antitumor sera raised against THE-2 cells interacted with these proteins at high efficiency. Antisera raised in animals bearing BKV-induced tumors were not used because all sera tested in these laboratories lacked detectable antibody to viral small t-antigens and recognized only large T-antigens of SV40 and BKV.Immunoprecipitates of BKV-infected HEK cells contained the viral proteins, T and t (21K), but also contained two proteins with apparent molecular weights of 56K and 32K (Fig. 1B). Electrophoretically similar 56K and 32K proteins were also present in immunoprecipitates of SV40-infected monkey kidney (CV-1) cells (Fig. 1C), but not in immunoprecipitates of cells infected with SV40 deletion mutants that lacked t-antigen (Fig. 1D). To determine whether the 56K and 32K proteins observed in immunoprecipitates of BKV-infected cells were cellular in origin, mixed extract experiments were done. Uninfected CV-1 cells were labeled with methionine and then mixe...

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“…Polyomavirus virions such as simian virus 40 (SV40) comprise proteins and DNA, and are able to enter the nucleus from the extracellular environment [3]. Substances such as SV40 tumor antigen and nuclear proteins migrate into the nucleus from the cytoplasm [4,5]. IgG with synthetic peptides containing nuclear localization signal such as that of SV40 tumor antigen could enter the nucleus from the cytoplasm by active transport through nuclear pore complexes (NPCs) [2,6].…”

Section: Introductionmentioning

confidence: 99%

Transportation Course of Macromolecules to the Nucleus from the Extracellular Environment: Steroid Hormones’ Cellular Entry Mode Revisited

Nishimura¹

2018

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Polyomavirus virions such as simian virus 40 (SV40), antinuclear antibodies such as immunoglobulin G (IgG) and steroid hormones all enter the nucleus from the extracellular environment. Testosterone-bovine serum albumin conjugate labeled with 2 nm colloidal gold (testosterone-BSA-gold) is taken up by endocytosis into target cells, and enter the nucleus through a similar route as SV40 nuclear migration. Upon injection into the vascular system of rats, IgG coupled with hydrocortisone also enters the hormone-target cell nuclei with intact antigenicity. These results suggest that steroid hormones could act as transporters to deliver exogenous macromolecules, e.g. drugs, into their target cell nuclei in vivo, although further studies are required on whether steroid hormones coupled with proteins exert genomic actions in the nucleus, etc. Finally, testosterone-BSA-gold seems to be isolated from the cytosol in the processes of nuclear entry. Together, these findings challenge the popular belief that steroid hormones mostly enter the cell in unbound form via uncontrolled passive diffusion.

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Simian virus 40 small-t protein is required for loss of actin cable networks in rat cells

Cited by 75 publications

References 36 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

Association of cellular 56,000- and 32,000-molecular-weight protein with BK virus and polyoma virus t-antigens

Transportation Course of Macromolecules to the Nucleus from the Extracellular Environment: Steroid Hormones’ Cellular Entry Mode Revisited

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