scholarly journals Rat c-raf oncogene activation by a rearrangement that produces a fused protein.

1987 ◽  
Vol 7 (3) ◽  
pp. 1226-1232 ◽  
Author(s):  
F Ishikawa ◽  
F Takaku ◽  
M Nagao ◽  
T Sugimura
Keyword(s):  
Long Terminal Repeat ◽  
Rous Sarcoma Virus ◽  
Cell Transfection ◽  
3T3 Cells ◽  
Rous Sarcoma ◽  
Oncogene Activation ◽  
Sarcoma Virus ◽  
Transforming Activity ◽  
Nih 3T3 ◽  
Transfection Assay

In a previous study, activated rat c-raf was detected by an NIH 3T3 cell transfection assay, and a rearrangement was demonstrated in the 5' half of the sequence of the gene. In the present study, the cDNAs of normal and activated rat c-raf were analyzed. Results showed that the activated c-raf gene is transcribed to produce a fused mRNA, in which the 5' half of the sequence is replaced by an unknown rat sequence. This mRNA codes a fused c-raf protein. The normal and activated c-raf cDNAs were each connected to the long terminal repeat of Rous sarcoma virus and transfected into NIH 3T3 cells. Only the activated form had transforming activity. We conclude that the rearrangement is responsible for the activation of c-raf.

Rat c-raf oncogene activation by a rearrangement that produces a fused protein

1987 ◽  
Vol 7 (3) ◽  
pp. 1226-1232
Author(s):  
F Ishikawa ◽  
F Takaku ◽  
M Nagao ◽  
T Sugimura
Keyword(s):  
Long Terminal Repeat ◽  
Rous Sarcoma Virus ◽  
Cell Transfection ◽  
3T3 Cells ◽  
Rous Sarcoma ◽  
Oncogene Activation ◽  
Sarcoma Virus ◽  
Transforming Activity ◽  
Nih 3T3 ◽  
Transfection Assay

In a previous study, activated rat c-raf was detected by an NIH 3T3 cell transfection assay, and a rearrangement was demonstrated in the 5' half of the sequence of the gene. In the present study, the cDNAs of normal and activated rat c-raf were analyzed. Results showed that the activated c-raf gene is transcribed to produce a fused mRNA, in which the 5' half of the sequence is replaced by an unknown rat sequence. This mRNA codes a fused c-raf protein. The normal and activated c-raf cDNAs were each connected to the long terminal repeat of Rous sarcoma virus and transfected into NIH 3T3 cells. Only the activated form had transforming activity. We conclude that the rearrangement is responsible for the activation of c-raf.

v-src mutations outside the carboxyl-coding region are not sufficient to fully activate transformation by pp60c-src in NIH 3T3 cells

1988 ◽  
Vol 8 (2) ◽  
pp. 704-712
Author(s):  
S Reddy ◽  
P Yaciuk ◽  
T E Kmiecik ◽  
P M Coussens ◽  
D Shalloway
Keyword(s):  
Rous Sarcoma Virus ◽  
Terminal Region ◽  
Cell Protein ◽  
Coding Region ◽  
3T3 Cells ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Carboxyl Terminal ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

Previous studies have shown that carboxyl-terminal mutation of pp60c-src can activate its transforming ability. Conflicting results have been reported for the transforming ability of pp60c-src mutants having only mutations outside its carboxyl-terminal region. To clarify the effects of such mutations, we tested the activities of chimeric v(amino)- and c(carboxyl)-src (v/c-src) proteins at different dosages in NIH 3T3 cells. The focus-forming activity of Rous sarcoma virus long terminal repeat (LTR)-src expression plasmids was significantly reduced when the v-src 3' coding region was replaced with the corresponding c-src region. This difference was masked when the Rous sarcoma virus LTR was replaced with the Moloney murine leukemia virus LTR, which induced approximately 20-fold more protein expression, but even focus-selected lines expressing v/c-src proteins were unable to form large colonies in soft agarose or tumors in NFS mice. This suggests that pp60c-src is not equally sensitive to mutations in its different domains and that there are at least two distinguishable levels of regulation, the dominant one being associated with its carboxyl terminus. v/c-src chimeric proteins expressed with either LTR had high in vitro specific kinase activity equal to that of pp60v-src but, in contrast, were phosphorylated at both Tyr-527 and Tyr-416. Total cell protein phosphotyrosine was enhanced in cells incompletely transformed by v/c-src proteins to the same extent as in v-src-transformed cells, suggesting that the carboxyl-terminal region may affect substrate specificity in a manner that is important for transformation.

scholarly journals v-src mutations outside the carboxyl-coding region are not sufficient to fully activate transformation by pp60c-src in NIH 3T3 cells.

1988 ◽  
Vol 8 (2) ◽  
pp. 704-712 ◽  
Author(s):  
S Reddy ◽  
P Yaciuk ◽  
T E Kmiecik ◽  
P M Coussens ◽  
D Shalloway
Keyword(s):  
Rous Sarcoma Virus ◽  
Terminal Region ◽  
Cell Protein ◽  
Coding Region ◽  
3T3 Cells ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Carboxyl Terminal ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

Previous studies have shown that carboxyl-terminal mutation of pp60c-src can activate its transforming ability. Conflicting results have been reported for the transforming ability of pp60c-src mutants having only mutations outside its carboxyl-terminal region. To clarify the effects of such mutations, we tested the activities of chimeric v(amino)- and c(carboxyl)-src (v/c-src) proteins at different dosages in NIH 3T3 cells. The focus-forming activity of Rous sarcoma virus long terminal repeat (LTR)-src expression plasmids was significantly reduced when the v-src 3' coding region was replaced with the corresponding c-src region. This difference was masked when the Rous sarcoma virus LTR was replaced with the Moloney murine leukemia virus LTR, which induced approximately 20-fold more protein expression, but even focus-selected lines expressing v/c-src proteins were unable to form large colonies in soft agarose or tumors in NFS mice. This suggests that pp60c-src is not equally sensitive to mutations in its different domains and that there are at least two distinguishable levels of regulation, the dominant one being associated with its carboxyl terminus. v/c-src chimeric proteins expressed with either LTR had high in vitro specific kinase activity equal to that of pp60v-src but, in contrast, were phosphorylated at both Tyr-527 and Tyr-416. Total cell protein phosphotyrosine was enhanced in cells incompletely transformed by v/c-src proteins to the same extent as in v-src-transformed cells, suggesting that the carboxyl-terminal region may affect substrate specificity in a manner that is important for transformation.

scholarly journals Effect of mycoplasma on polyamine synthesis and levels in NIH 3T3 cells and in cells transformed by Rous sarcoma virus

1988 ◽  
Vol 49 (3) ◽  
pp. 357-361
Author(s):  
Rajbabu Pakala ◽  
Reuven Laskov ◽  
Shlomo Rottem ◽  
Uriel Bachrach
Keyword(s):  
Rous Sarcoma Virus ◽  
3T3 Cells ◽  
Polyamine Synthesis ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Nih 3T3 ◽  
Nih 3T3 Cells ◽  
In Cells

Identification of transcriptional elements within the long terminal repeat of Rous sarcoma virus

1983 ◽  
Vol 3 (10) ◽  
pp. 1834-1845
Author(s):  
G M Gilmartin ◽  
J T Parsons
Keyword(s):  
Long Terminal Repeat ◽  
Virus Replication ◽  
Rous Sarcoma Virus ◽  
Regulatory Elements ◽  
Terminal Repeat ◽  
Tata Box ◽  
Transcriptional Regulatory Elements ◽  
Rous Sarcoma ◽  
Transcriptional Regulatory ◽  
Sarcoma Virus

Transcriptional regulatory elements within the Rous sarcoma virus long terminal repeat were examined by the construction of a series of deletions and small insertions within the U3 region of the long terminal repeat. The analysis of these mutations in chicken embryo cells and COS cells permitted the identification of important transcriptional regulatory elements. Sequences within the region 31 to 18 base pairs upstream of the RNA cap site (-31 to -18), encompassing a TATA box-like sequence, function in the selection of the correct site of transcription initiation and, in addition, augment the efficiency of transcription. These sequences are essential for virus replication. Sequences within the region -79 to -59, overlapping a CAAT box-like sequence, are not required for virus replication and have no obvious effect on viral RNA transcription in the presence of an intact TATA box. However, in mutants lacking a functional TATA sequence, mutations in this region serve to decrease the efficiency of correct transcriptional initiation events.

scholarly journals The first seven amino acids encoded by the v-src oncogene act as a myristylation signal: lysine 7 is a critical determinant.

1988 ◽  
Vol 8 (6) ◽  
pp. 2435-2441 ◽  
Author(s):  
J M Kaplan ◽  
G Mardon ◽  
J M Bishop ◽  
H E Varmus
Keyword(s):  
Amino Acids ◽  
Rous Sarcoma Virus ◽  
Subcellular Location ◽  
Membrane Association ◽  
Recognition Sequence ◽  
Critical Determinant ◽  
Amide Linkage ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Transforming Activity

The transforming protein of Rous sarcoma virus, pp60v-src, is covalently coupled to myristic acid by an amide linkage to glycine 2. Myristylation promotes the association of pp60v-src with cellular membranes, and this subcellular location is essential for transforming activity. The findings presented here, in conjunction with the previous reports of others, imply that the seventh amino acid encoded by v-src might be important in the myristylation reaction. Replacement of lysine 7 by asparagine greatly reduced the myristylation, membrane association, and transforming activity of pp60v-src. In contrast, substitution of arginine at residue 7 had no effect on any of these properties of pp60v-src. Addition of amino acids 1 to 7 encoded by v-src was sufficient to cause myristylation of a src-pyruvate kinase fusion protein. We conclude that the recognition sequence for myristylation of pp60v-src comprises amino acids 1 to 7 and that lysine 7 is a critical component of this sequence.

Transformation of NIH/3T3 mouse cells by DNA of Rous sarcoma virus

Cell ◽  
1979 ◽  
Vol 17 (4) ◽  
pp. 993-1002 ◽  
Author(s):  
Neal G. Copeland ◽  
Andrew D. Zelenetz ◽  
Geoffrey M. Cooper
Keyword(s):  
Rous Sarcoma Virus ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Mouse Cells ◽  
Nih 3T3

scholarly journals Transformation of NIH 3T3 cells by cotransfection with c-src and nuclear oncogenes.

1987 ◽  
Vol 7 (10) ◽  
pp. 3582-3590 ◽  
Author(s):  
D Shalloway ◽  
P J Johnson ◽  
E O Freed ◽  
D Coulter ◽  
W A Flood
Keyword(s):  
3T3 Cells ◽  
Focus Formation ◽  
Adenovirus E1a ◽  
Rous Sarcoma ◽  
Cellular Homolog ◽  
Sarcoma Virus ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

pp60c-src, the cellular homolog of the Rous sarcoma virus transforming protein, does not completely transform cells even when present at high levels, but has been shown to be involved in polyomavirus-induced transformation when activated by polyomavirus middle T (pmt)-antigen binding. Here we show that cotransfection, but not solo transfection, of expression plasmids for c-src and either adenovirus E1A, v-myc, c-myc, or the 5' half of polyomavirus large T (pltN) antigen into NIH 3T3 cells induces anchorage-independent growth, enhanced focus formation, and, for pltN cotransfection, tumorigenicity in adult NFS mice. Enhancement of transformation was not observed with polyomavirus small t (pst) antigen. Cotransfection of c-src with pltN induced modification of pp60c-src that altered its electrophoretic mobility and in vivo phosphorylation state and stimulated its in vitro kinase activity. Similar alterations were not seen after c-src-E1A cotransfection, suggesting that at least two different mechanisms of enhancement are involved.

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