Cell-Density Control of Amino Acid Transport in Simian Virus 40-Transformed 3T3 Cells

1979 ◽  
Vol 7 (5) ◽  
pp. 1137-1139 ◽  
Author(s):  
GIUSEPPE PIEDIMONTE ◽  
MARIAROSARIA TRAMACERE ◽  
ANGELO F. BORGHETTI
Keyword(s):  
Amino Acid ◽  
Cell Density ◽  
Amino Acid Transport ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Acid Transport ◽  
3T3 Cells ◽  
Density Control

Cell-dependent efficiency of reiterated nuclear signals in a mutant simian virus 40 oncoprotein targeted to the nucleus

1988 ◽  
Vol 8 (12) ◽  
pp. 5495-5503
Author(s):  
L Fischer-Fantuzzi ◽  
C Vesco
Keyword(s):  
Amino Acid ◽  
Nuclear Transport ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
3T3 Cells ◽  
Rat Embryo ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

We investigated the requisites for, and functional consequences of, the relocation to the nucleus of a transforming nonkaryophilic mutant of the simian virus 40 large T antigen (a natural deletion mutant lacking an internal large-T-antigen domain that includes the signal for nuclear transport). Synthetic oligonucleotides were used to obtain gene variants with one or more copies of the signal-specifying sequence inserted near the gene 3' end, in a region dispensable for the main large-T-antigen functions. The analysis of stable transfectant populations showed that mouse NIH 3T3 cells, rat embryo fibroblasts, and simian CS cells (a subclone of CV1 cells) differed considerably in their ability to localize some variant molecules into the nucleus. CS cells were always the most efficient, and NIH 3T3 cells were the least efficient. The nuclear localization improved either with reiteration of the signal or with a left-flank modification of the signal amino acid context. Three signals appeared to be necessary and sufficient, even in NIH 3T3 cells, to obtain a nuclear accumulation comparable to that of wild-type simian virus 40 large T antigen; other signal-cell combinations caused a large variability in subcellular localization among cells of the same population, as if the nuclear uptake of some molecules depended on individual cell states. The effect of the modified location on the competence of the protein to alter cell growth was examined by comparing the activity of variants containing either the normal signal or a signal with a mutation (corresponding to large-T-antigen amino acid 128) that prevented nuclear transport. It was found that the nuclear variant was slightly more active than the cytoplasmic variants in rat embryo fibroblasts and NIH 3T3 cells and was notably less active in CS cells.

The effect of heat shock on amino acid transport and cell volume in 3T3 cells

Amino Acids ◽  
2001 ◽  
Vol 20 (4) ◽  
pp. 363-380 ◽  
Author(s):  
P. G. Petronini ◽  
A. E. Caccamo ◽  
R. R. Alfieri ◽  
M. A. Bonelli ◽  
A. F. Borghetti
Keyword(s):  
Amino Acid ◽  
Heat Shock ◽  
Cell Volume ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
3T3 Cells

scholarly journals Modulation by betaine of cellular responses to osmotic stress

1992 ◽  
Vol 282 (1) ◽  
pp. 69-73 ◽  
Author(s):  
P G Petronini ◽  
E M De Angelis ◽  
P Borghetti ◽  
A F Borghetti ◽  
K P Wheeler
Keyword(s):  
Cell Proliferation ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Cell Protein ◽  
Acid Transport ◽  
3T3 Cells ◽  
Functional Responses ◽  
Cell Functions ◽  
System A

Various solutes were tested to see if they could modify the responses of SV-3T3 cells to hyperosmotic (0.5 osM) conditions, which cause an inhibition of general cell protein synthesis and of the rate of cell proliferation, coupled with an induction of amino acid transport activity. The added solutes were glycerol, proline, taurine, betaine, dimethylglycine and sarcosine. Of these, betaine produced the most dramatic and consistent effects. Addition of 10-25 mM-betaine to the hyperosmotic medium largely prevented the 90% inhibition of cell proliferation that occurred in its absence. Whether it was added initially or after the cells were exposed to hyperosmotic medium, 25 mM-betaine also converted a 50% recovery of the rate of protein synthesis into 100%. Similarly, the same concentrations of betaine prevented a 30% decrease in cell volume and decreased the induction of amino acid transport via system A by 73%. Lower concentrations of betaine produced smaller but still significant changes in these functional responses. With chick-embryo fibroblasts, under identical hyperosmotic conditions, 25 mM-betaine completely counteracted a 75% inhibition of the rate of protein synthesis. At present it is not clear how betaine modulates these effects of hyperosmolarity on cell functions.

Cell density and amino acid transport in 3T3, SV3T3, and SV3T3 revertant cells

1980 ◽  
Vol 105 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Angelo F. Borghetti ◽  
Giuseppe Piedimonte ◽  
Mariarosaria Tramacere ◽  
Alberto Severini ◽  
Paolo Ghiringhelli ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cell Density ◽  
Amino Acid Transport ◽  
Acid Transport

scholarly journals Cell-dependent efficiency of reiterated nuclear signals in a mutant simian virus 40 oncoprotein targeted to the nucleus.

1988 ◽  
Vol 8 (12) ◽  
pp. 5495-5503 ◽  
Author(s):  
L Fischer-Fantuzzi ◽  
C Vesco
Keyword(s):  
Amino Acid ◽  
Nuclear Transport ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
3T3 Cells ◽  
Rat Embryo ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

We investigated the requisites for, and functional consequences of, the relocation to the nucleus of a transforming nonkaryophilic mutant of the simian virus 40 large T antigen (a natural deletion mutant lacking an internal large-T-antigen domain that includes the signal for nuclear transport). Synthetic oligonucleotides were used to obtain gene variants with one or more copies of the signal-specifying sequence inserted near the gene 3' end, in a region dispensable for the main large-T-antigen functions. The analysis of stable transfectant populations showed that mouse NIH 3T3 cells, rat embryo fibroblasts, and simian CS cells (a subclone of CV1 cells) differed considerably in their ability to localize some variant molecules into the nucleus. CS cells were always the most efficient, and NIH 3T3 cells were the least efficient. The nuclear localization improved either with reiteration of the signal or with a left-flank modification of the signal amino acid context. Three signals appeared to be necessary and sufficient, even in NIH 3T3 cells, to obtain a nuclear accumulation comparable to that of wild-type simian virus 40 large T antigen; other signal-cell combinations caused a large variability in subcellular localization among cells of the same population, as if the nuclear uptake of some molecules depended on individual cell states. The effect of the modified location on the competence of the protein to alter cell growth was examined by comparing the activity of variants containing either the normal signal or a signal with a mutation (corresponding to large-T-antigen amino acid 128) that prevented nuclear transport. It was found that the nuclear variant was slightly more active than the cytoplasmic variants in rat embryo fibroblasts and NIH 3T3 cells and was notably less active in CS cells.

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