Quantitation of a 55K cellular protein: similar amount and instability in normal and malignant mouse cells

1982 ◽  
Vol 2 (7) ◽  
pp. 763-771
Author(s):  
P T Mora ◽  
K Chandrasekaran ◽  
J C Hoffman ◽  
V W McFarland
Keyword(s):  
Half Life ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Cellular Protein ◽  
T Antigen ◽  
Similar Amount ◽  
Parent Cell ◽  
Primary Cells ◽  
Quantitative Expression ◽  
Tumorigenic Cells

Quantitative expression of a specific 55,000 (55K)-molecular-weight cellular protein was studied in two groups of mouse embryo fibroblast (clonal) cells originating from two parent clones, one of which possessed high tumorigenicity and the other of which possessed very low tumorigenicity. From the clone with low tumorigenicity, tumor lines and clones were obtained by selecting rare spontaneously transformed highly tumorigenic (mutant) cells. Cells were labeled during exponential growth for 3 h at 37 degrees C, with [35S]methionine, and the cellular 55K protein was immunoprecipitated with a monoclonal antibody and quantitated. There were low and approximately equal amounts of 55K protein in cells (clones) with both low and high tumorigenicity from both groups of cells, and there was no correlation at all between quantitative expression of 55K protein and of cellular tumorigenicity. There was approximately 10- to 20-fold more 55K protein in all simian virus 40-transformed T antigen-positive derivative clones, as shown previously. The T antigen-negative revertant tumor lines and clones obtained by an immunological in vivo selection method had low amounts of 55K protein, similar to the parent cell before simian virus 40 transformation. In all of the T antigen-negative cells, including the highly tumorigenic cells, degradation (turnover?) of the 55K protein was rapid, and a half-life of 15 to 60 min was estimated from pulse-chase experiments. In all of the T antigen-positive cells the 55K protein was stable (half-life greater than 10 h). In primary cells established from the tumors induced by highly tumorigenic cells there was a very low or no detectable amount of the 55K protein. This is in contrast to the primary cells obtained from early murine embryos in which we have reported high amounts of (stable) 55K proteins.

scholarly journals Quantitation of a 55K cellular protein: similar amount and instability in normal and malignant mouse cells.

1982 ◽  
Vol 2 (7) ◽  
pp. 763-771 ◽  
Author(s):  
P T Mora ◽  
K Chandrasekaran ◽  
J C Hoffman ◽  
V W McFarland
Keyword(s):  
Half Life ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Cellular Protein ◽  
T Antigen ◽  
Similar Amount ◽  
Parent Cell ◽  
Primary Cells ◽  
Quantitative Expression ◽  
Tumorigenic Cells

Quantitative expression of a specific 55,000 (55K)-molecular-weight cellular protein was studied in two groups of mouse embryo fibroblast (clonal) cells originating from two parent clones, one of which possessed high tumorigenicity and the other of which possessed very low tumorigenicity. From the clone with low tumorigenicity, tumor lines and clones were obtained by selecting rare spontaneously transformed highly tumorigenic (mutant) cells. Cells were labeled during exponential growth for 3 h at 37 degrees C, with [35S]methionine, and the cellular 55K protein was immunoprecipitated with a monoclonal antibody and quantitated. There were low and approximately equal amounts of 55K protein in cells (clones) with both low and high tumorigenicity from both groups of cells, and there was no correlation at all between quantitative expression of 55K protein and of cellular tumorigenicity. There was approximately 10- to 20-fold more 55K protein in all simian virus 40-transformed T antigen-positive derivative clones, as shown previously. The T antigen-negative revertant tumor lines and clones obtained by an immunological in vivo selection method had low amounts of 55K protein, similar to the parent cell before simian virus 40 transformation. In all of the T antigen-negative cells, including the highly tumorigenic cells, degradation (turnover?) of the 55K protein was rapid, and a half-life of 15 to 60 min was estimated from pulse-chase experiments. In all of the T antigen-positive cells the 55K protein was stable (half-life greater than 10 h). In primary cells established from the tumors induced by highly tumorigenic cells there was a very low or no detectable amount of the 55K protein. This is in contrast to the primary cells obtained from early murine embryos in which we have reported high amounts of (stable) 55K proteins.

Maintenance of cellular proliferation by adenovirus early region 1A in fibroblasts conditionally immortalized by using simian virus 40 large T antigen requires conserved region 1

1990 ◽  
Vol 10 (12) ◽  
pp. 6664-6673
Author(s):  
T E Riley ◽  
A Follin ◽  
N C Jones ◽  
P S Jat
Keyword(s):  
Cell Line ◽  
Growth Arrest ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Growth Defect ◽  
Primary Cells ◽  
Nonpermissive Temperature ◽  
Large T Antigen ◽  
Adenovirus E1a

Various mutants of adenovirus E1A were assayed for their ability to complement the growth defect at the nonpermissive temperature for the cell line tsa14 which was isolated by immortalizing rat embryo fibroblasts with the thermolabile large T antigen of tsA58. This cell line grows indefinitely at the permissive temperature but undergoes rapid growth arrest upon shift up to the nonpermissive temperature. Since this growth arrest can be overcome by introduction of wild-type simian virus 40 large T antigen, human papillomavirus 16 E7, and adenovirus E1A, the tsa14 cells provided an excellent system for defining regions of E1A necessary for complementation of the growth defect. We demonstrate that conserved region 1 (CR1) is the region of E1A required for complementation. While CR2 of E1A has been shown to be required for the immortalization of primary cells and is also necessary for the binding of the 105-kDa retinoblastoma protein, mutations within this region did not abrogate complementation of the growth defect. However, since both CR1 and CR2 have previously been shown to be absolutely required for immortalization of primary cells by adenovirus E1A, this evidence suggests that the tsa14 system assays for the maintenance of proliferation and that this requires CR1.

scholarly journals Maintenance of cellular proliferation by adenovirus early region 1A in fibroblasts conditionally immortalized by using simian virus 40 large T antigen requires conserved region 1.

1990 ◽  
Vol 10 (12) ◽  
pp. 6664-6673 ◽  
Author(s):  
T E Riley ◽  
A Follin ◽  
N C Jones ◽  
P S Jat
Keyword(s):  
Cell Line ◽  
Growth Arrest ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Growth Defect ◽  
Primary Cells ◽  
Nonpermissive Temperature ◽  
Large T Antigen ◽  
Adenovirus E1a

Various mutants of adenovirus E1A were assayed for their ability to complement the growth defect at the nonpermissive temperature for the cell line tsa14 which was isolated by immortalizing rat embryo fibroblasts with the thermolabile large T antigen of tsA58. This cell line grows indefinitely at the permissive temperature but undergoes rapid growth arrest upon shift up to the nonpermissive temperature. Since this growth arrest can be overcome by introduction of wild-type simian virus 40 large T antigen, human papillomavirus 16 E7, and adenovirus E1A, the tsa14 cells provided an excellent system for defining regions of E1A necessary for complementation of the growth defect. We demonstrate that conserved region 1 (CR1) is the region of E1A required for complementation. While CR2 of E1A has been shown to be required for the immortalization of primary cells and is also necessary for the binding of the 105-kDa retinoblastoma protein, mutations within this region did not abrogate complementation of the growth defect. However, since both CR1 and CR2 have previously been shown to be absolutely required for immortalization of primary cells by adenovirus E1A, this evidence suggests that the tsa14 system assays for the maintenance of proliferation and that this requires CR1.

scholarly journals Establishment and characterization of transformed goat primary cells by expression of simian virus 40 large T antigen for orf virus propagations

PLoS ONE ◽  
2019 ◽  
Vol 14 (12) ◽  
pp. e0226105
Author(s):  
Yumiko Yamada ◽  
Guan-Ru Liao ◽  
Ching-Yu Tseng ◽  
Yeu-Yang Tseng ◽  
Wei-Li Hsu
Keyword(s):  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Orf Virus ◽  
Primary Cells ◽  
Large T Antigen

scholarly journals Two Independent Regions of Simian Virus 40 T Antigen Increase CBP/p300 Levels, Alter Patterns of Cellular Histone Acetylation, and Immortalize Primary Cells

2013 ◽  
Vol 87 (24) ◽  
pp. 13499-13509 ◽  
Author(s):  
M. T. Saenz Robles ◽  
C. Shivalila ◽  
J. Wano ◽  
S. Sorrells ◽  
A. Roos ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Primary Cells

scholarly journals A new member of the hsp90 family of molecular chaperones interacts with the retinoblastoma protein during mitosis and after heat shock.

1996 ◽  
Vol 16 (9) ◽  
pp. 4691-4699 ◽  
Author(s):  
C F Chen ◽  
Y Chen ◽  
K Dai ◽  
P L Chen ◽  
D J Riley ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Mammalian Cells ◽  
Retinoblastoma Protein ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Cellular Protein ◽  
T Antigen ◽  
Single Mutation

A gene encoding a new heat shock protein that may function as a molecular chaperone for the retinoblastoma protein (Rb) was characterized. The cDNA fragment was isolated by using the yeast two-hybrid system and Rb as bait. The open reading frame of the longest cDNA codes for a protein with substantial sequence homology to members of the hsp90 family. Antibodies prepared against fusions between glutathione S-transferase and portions of this new heat shock protein specifically recognized a 75-kDa cellular protein, hereafter designated hsp75, which is expressed ubiquitously and located in the cytoplasm. A unique LxCxE motif in hsp75, but not in other hsp90 family members, appears to be important for binding to the simian virus 40 T-antigen-binding domain of hypophosphorylated Rb, since a single mutation changing the cysteine to methionine abolishes the binding. In mammalian cells, Rb formed complexes with hsp75 under two special physiological conditions: (i) during M phase, when the envelope that separates the nuclear and cytoplasmic compartments broke down, and (ii) after heat shock, when hsp75 moved from its normal cytoplasmic location into the nucleus. In vitro, hsp75 had a biochemical activity to refold denatured Rb into its native conformation. Taken together, these results suggest that Rb may be a physiological substrate for the hsp75 chaperone molecule. The discovery of a heat shock protein that chaperones Rb identifies a mechanism, in addition to phosphorylation, by which Rb is regulated in response to progression of the cell cycle and to external stimuli.

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