Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Genes, src”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1986

Characterization of transforming viruses rescued from a hamster tumour cell line harbouring the v-src gene flanked by long terminal repeats.

The organization of proviruses derived from infecting transforming viruses rescued from hamster tumour cells was studied. Southern blot analysis indicated that the provirus from the F6 cell line was organized as long terminal repeat (LTR)-src-LTR, and S1 mapping experiments suggested that it was probably derived by reverse transcription of src mRNA followed by integration. In the E6 cell line, the provirus unit was arranged as LTR-delta gag-src-LTR, indicating a recombination event between the rescued transforming virus and the helper virus. These results suggest that transforming defective viruses containing only the src gene can be rescued from nonpermissive mammalian cells.

Animals↗
PubMed1990

Analysis of mutant forms of the c-src gene product containing a phenylalanine substitution for tyrosine 416.

Several lines of evidence suggest that phosphorylation of tyrosine residue 416 (Tyr416) has a positive regulatory influence on the functional activity of the protein tyrosine kinase pp60c-src. To further examine the functional importance of phosphorylation at Tyr416, we have eliminated this phosphoacceptor site in four functionally unique mutant forms of the c-src gene product that are phosphorylated on Tyr416 in vivo. Substitution of phenylalanine for Tyr416 suppressed the biological activity of all of the mutant proteins as assayed by colony formation in soft agar and the induction of morphological alterations. However, the extent of this effect, and the degree to which the substitution affected the phosphorylation of substrates in vivo and in vitro, varied considerably in each of the mutants. These results support the notion that phosphorylation of Tyr416 has a positive regulatory effect on the biological activity of c-src; however, this effect does not directly correlate with a general effect on the total level of tyrosine kinase activity in vitro or the level of tyrosine phosphorylation of cellular proteins in vivo.

Animals↗
PubMed1996

Selection and characterization of replication-competent revertants of a Rous sarcoma virus src gene oversplicing mutant.

All retroviruses require both unspliced and spliced RNA for a productive infection. One mechanism by which Rous sarcoma virus achieves incomplete splicing involves suboptimal env and src 3' splice sites. We have previously shown that mutagenesis of the nonconsensus src polypyrimidine tract to a 14-nucleotide uninterrupted polypyrimidine tract results in an oversplicing phenotype and a concomitant defective replication in permissive chicken embryo fibroblasts. In this report, we show that splicing at the src 3' splice site (3'ss) is further negatively regulated by the suppressor of src splicing cis element which is located approximately 100 nucleotides upstream of the src 3'ss. The increase in splicing at the src 3'ss results in a corresponding increase in splicing at a cryptic 5'ss within the env gene. Two classes of replication-competent revertants of the src oversplicing mutant (pSAP1) were produced after infection, and these mutants were characterized by molecular cloning and sequence analysis. Class I revertants are transformation-defective revertants in which the src 3'ss and the src gene are deleted by homologous recombination at several different sites within the imperfect direct repeat sequences that flank the src gene. Cells infected with these transformation-defective revertants produce lower levels of virus particles than cells infected with the wild-type virus. Class II revertants bear small deletions in the region containing the branchpoint sequence or polypyrimidine tract of the src 3'ss. Insertion of these mutated sequences into pSAP1 restored inefficient splicing at the src 3'ss and efficient replication in chicken embryo fibroblasts. All of these mutations caused reduced splicing at the src 3'ss when they were tested in an in vitro splicing system. These results indicate that maintenance of a weak src 3'ss is necessary for efficient Rous sarcoma virus replication.

Animals↗
PubMed1985

Lack of induction of neuroretinal cell proliferation by Rous sarcoma virus variants that carry the c-src gene.

Expression of p60v-src of Rous sarcoma virus in cultured chicken embryo neuroretinal cells was previously shown to result in the transformation and sustained proliferation of normally quiescent cell populations. We show here that Rous sarcoma virus variants that encode p60c-src, the cellular homolog of p60v-src, lack the ability to induce morphological transformation and cell proliferation of cultured neuroretinal cells. Neuroretinal cells infected with c-src-containing viruses, however, possess no less p60 protein kinase activity assayed in the immune complex than those infected with the transformation-defective Rous sarcoma virus mutants PA101 or PA104, which do stimulate the growth of these cells.

Animals↗
PubMed1984

Common features of the yes and src gene products defined by peptide-specific antibodies.

Anti-peptide antibodies generated against a hydrophilic domain of pp60src comprising amino acid residues 498 through 512 were shown to be cross-reactive with the corresponding region in the yes transforming proteins encoded by Yamaguchi 73 and Esh sarcoma viruses. This cross-reactivity was demonstrated by immunoblot and immunoprecipitation analyses, and the identity of the proteins was verified by partial proteolytic mapping. By utilizing a combination of immunofluorescence and interference-reflection microscopy, these cross-reactive anti-peptide antibodies were shown to produce an immunofluorescence staining pattern in Yamaguchi 73 and Esh sarcoma virus-transformed chicken embryo fibroblasts remarkably similar to that pp60src in Rous sarcoma virus-infected chicken cells. Like the src gene products, the yes transformation-specific polyproteins were found to be concentrated within adhesion plaque structures and needle-like interdigitating cell-cell junctions. This analogous subcellular distribution suggests that these onc proteins are functionally related and may share common intracellular targets.

Amino Acid Sequence↗
PubMed1997

Prognostic factors for fibromatoses: a correlation of proliferation index, estrogen receptor, p53, retinoblastoma, and src gene products and clinical features with outcome.

BACKGROUND: The aggressiveness of fibromatoses is difficult to predict by morphologic analysis. Additional prognostic markers would be helpful for clinical management. MATERIALS AND METHODS: Proliferation index (MIB-1), p53, src, retinoblastoma gene protein products, estrogen receptor level, site and depth of lesion were correlated with incidence of recurrence in 52 patients. Superficial (47) and deep (5) fibromatoses were studied. Anatomic sites included the extremities, head, neck, trunk, and pelvis. RESULTS: Twenty (38%) lesions recurred locally. All five deep lesions recurred, but only 32% of superficial tumors recurred. Mean proliferation index for recurrent lesions was 0.82% and 0.73% for nonrecurrent fibromatoses; no significant differences were observed. Five recurrent lesions (25%) expressed estrogen receptor > 5 fmol/mg as did 31% (10 of 32) of the nonrecurrent lesions. None of the tested specimens expressed src gene product. Eight of the lesions which recurred (40%) contained p53, but only five nonrecurring tumors (16%) expressed p53. One of five deep lesions (20%) expressed p53 and 26% (12 of 47) of superficial tumors expressed p53. Forty-six percent (6 of 13) of recurrent lesions tested were retinoblastoma protein product negative, but only 33.3% (7 of 21) of nonrecurring tumors were retinoblastoma protein product negative. CONCLUSIONS: Only p53 and depth of lesion were of statistical value for the prediction of recurrence.

Biomarkers, Tumor↗
PubMed1985

Highly specific antibody to Rous sarcoma virus src gene product recognizes a novel population of pp60v-src and pp60c-src molecules.

Antiserum to the Rous sarcoma virus (RSV)-transforming protein, pp60v-src, was produced in rabbits immunized with p60 expressed in Escherichia coli. alpha p60 serum immunoprecipitated quantitatively more pp60v-src than did tumor-bearing rabbit (TBR) sera. When RSV-transformed cell lysates were preadsorbed with TBR serum, the remaining lysate contained additional pp60v-src, which was recognized only by reimmunoprecipitation with alpha p60 serum and not by TBR serum. In subcellular fractions of RSV-infected chicken embryo fibroblasts (RSV-CEFs) and field vole cells probed with TBR serum, the majority of the pp60v-src was associated with the plasma membrane-enriched P100 fraction. However, alpha p60 serum revealed equal distribution of pp60v-src and its kinase activity between the P1 (nuclear) and P100 fractions. The same results were obtained for pp60c-src in uninfected CEFs. On discontinuous sucrose gradients nearly 50% of the P1-pp60v-src sedimented with nuclei, in fractions where no plasma membrane was detected. Indirect immunofluorescence microscopy of RSV-CEFs with alpha p60 serum revealed a distinct pattern of perinuclear fluorescence, in addition to staining at the cell periphery. Thus the use of a highly specific antibody reveals that enzymatically active pp60v-src and pp60c-src molecules are present in other intracellular structures, probably juxtareticular nuclear membranes, in addition to the plasma membrane in normal, uninfected, and wild-type RSV-infected cells.

Animals↗
PubMed1989

v-src genes stimulate neurite outgrowth in pheochromocytoma (PC12) variants unresponsive to neurotrophic factors.

The NGF-nonresponsive rat pheochromocytoma PC12 variant nnr5, isolated by Green et al. (J Cell Biol 102:830-843, 1986), responds poorly or not at all to fibroblast growth factor. Transformation of PC-12nnr5 cells with v-src-expressing retroviruses results in vigorous neurite outgrowth, similar to that seen in the parent cell line. Thus though the PC12nnr5 cell line has a greatly impaired ability to respond to neurotrophic factors it still may extend neurites. This data is consistent with a model in which PC12nnr5 cells are unable to propagate intracellular second messengers, and this defect may be related to the expression of c-src gene products.

Animals↗
PubMed1985

N-terminal deletions in Rous sarcoma virus p60src: effects on tyrosine kinase and biological activities and on recombination in tissue culture with the cellular src gene.

We have constructed deletions within the region of cloned Rous sarcoma virus DNA coding for the N-terminal 30 kilodaltons of p60src. Infectious virus was recovered after transfection. Deletions of amino acids 15 to 149, 15 to 169, or 149 to 169 attenuated but did not abolish transforming activity, as assayed by focus formation and anchorage-independent growth. These deletions also had only slight effects on the tyrosine kinase activity of the mutant src protein. Deletion of amino acids 169 to 264 or 15 to 264 completely abolished transforming activity, and src kinase activity was reduced at least 10-fold. However, these mutant viruses generated low levels of transforming virus by recombination with the cellular src gene. The results suggest that as well as previously identified functional domains for p60src myristylation and membrane binding (amino acids 1 to 14) and tyrosine kinase activity (amino acids 250 to 526), additional N-terminal sequences (particularly amino acids 82 to 169) can influence the transforming activity of the src protein.

Animals↗
PubMed1984

Intercellular communication and the control of growth: X. Alteration of junctional permeability by the src gene. A study with temperature-sensitive mutant Rous sarcoma virus.

To study changes of junctional membrane permeability associated with transformation, the junctions and the nonjunctional membranes of quail embryo-, chick embryo- and mouse-3T3 cell cultures, infected with temperature-sensitive mutant Rous sarcoma virus, were probed with fluorescent-labelled glutamate. Junctional permeability fell in the transformed state. In the quail cells, the fall was detectable within 25 min of shifting the temperature down to the level (permissive) at which tyrosine-phosphorylation by the viral src gene product is expressed. This reduction of junctional permeability is one of the earliest manifestations of viral transformation. Normal permeability was restored within 30 min of raising the temperature to the nonpermissive level, a reversibility that could be displayed several times during the span of a cell generation. The reversal seems to reflect a reopening of cell-to-cell channels rather than a synthesis of new ones; it is not blocked by protein-synthesis inhibition. Treatments with cyclic AMP and phosphodiesterase inhibitor or with forskolin, which stimulate serine and threonine phosphorylation--the type of phosphorylation on which normal junctional permeability depends (Wiener & Loewenstein, 1983, Nature 305:433)--did not abolish, in general, the junctional effect of the virus; src tyrosine-phosphorylation apparently overrides the junctional upregulation mediated by cyclic AMP. Nonjunctional membrane permeability was not sensibly affected by the virus. It was affected, however, by temperature: lowering the temperature from the nonpermissive to the permissive level caused the nonjunctional permeability to fall, and vice versa. This change was unrelated to transformation. Its secondary effect on junctional transfer is in the opposite direction to that produced by the temperature-activated viral transformation.

Animals↗
PubMed1979

Product of in vitro translation of the Rous sarcoma virus src gene has protein kinase activity.

In vitro translation of Rous sarcoma virus virion RNA resulted in the synthesis of a protein kinase which, when immunoprecipitated with antitumor serum, phosphorylated the immunoglobulin heavy chain. Even though in vitro translation of virion RNA resulted in the synthesis of a number of polypeptides which were recognized by antitumor serum, control experiments demonstrated that an immunoprecipitable protein kinase activity was found only when an immunoprecipitable p60src, the polypeptide product of the src gene, was synthesized. A protein kinase with similar properties was therefore intimately associated with p60src which was synthesized in vitro in the reticulocyte lysate, just as it is with p60src which is obtained from transformed chick and mammalian cells. It is therefore highly unlikely that this association is artifactual. ts NY68 is a mutant of Rous sarcoma virus which is able to transform cells at 36 but not at 41 degrees C. In vitro translation of ts NY68 virion RNA at 30 degrees C resulted in efficient synthesis of immunoprecipitable p60src, but very inefficient synthesis of an immunoprecipitable protein kinase. The p60src obtained by in vitro translation of wild-type virion RNA was more than 20-fold more active as a protein kinase than was that obtained from ts NY68 RNA. The correlation in the case of ts NY68 of a deficiency in protein kinase activity with an inability to transform cells at high temperature suggests that the protein kinase activity associated with p60src is indeed critical to cellular transformation.

Avian Sarcoma Viruses↗
PubMed1983

The erbB gene of avian erythroblastosis virus is a member of the src gene family.

The erbB gene of an avian erythroblastosis virus, AEV-H, was determined to be 1812 nucleotides long and was predicted to code for a protein of 67,638 daltons. Unexpectedly, a sequence of 285 amino acids in the middle of the protein showed a significant homology (38%) with the sequence in the carboxy terminus of p60src. The nucleotide sequence of a mutant of AEV-H, td-130, which induces sarcomas but not erythroblastosis in chicken, was also analyzed. A deletion of 169 nucleotides was identified in the 3' half of the erbB gene, indicating that the gene codes for a truncated protein with the predicted molecular weight of 46,667. These findings suggest that the homologous domain of erbB protein with its N-terminal portion is sufficient for the transformation of fibroblasts and that one-third of the carboxy-terminal domain has a key role for the transformation of erythroid cells.

Alpharetrovirus↗
PubMed1985

Rous sarcoma virus SRC gene expression on the growth of quail embryo skin fibroblasts and the establishment of permanent cell lines.

Permanent cell lines of Quail embryo fibroblasts appear in cultures of cells infected with a wild type strain of Rous sarcoma virus (SR-RSV) or with its temperature sensitive transformation mutants (ts-T) (NYts68 and PA101) following a three step process. In step one, infected cells grow twice as fast as the control. The second step consists of a crisis during which the cell population is stationary for four to five weeks. Towards the fourth week several foci of cell growth are observed in the flasks. Respreading of the content of these flasks yields permanent lines. This constitutes the third step of the population evolution. In step one the growth rate of the infected cells is the same irrespective of the incubation temperature (36 degrees C or 41 degrees C) whereas the level of the pp60v-src activity is considerably depressed at 41 degrees C for NYts68 and PA101. Foci do not appear at restrictive temperature in the ts infected population and permanent lines are not recovered under that condition. These lines grow ony at 36 degrees C. It can be shown that the virus which they produce is not modified with respect to the temperature sensitivity of the src gene expression since newly infected fibroblasts grow equally well in step one at both 36 degrees C and 41 degrees C, and stop after the same number of generations. This finding suggests that the events which, during the crisis period, lead to the establishment of permanent lines, take place at the cellular level but depend on the activity of the pp60v-src protein for their occurrence or their expression.

Animals↗
PubMed1984

Intercellular communication and the control of growth: XI. Alteration of junctional permeability by the src gene in a revertant cell with normal cytoskeleton.

To learn whether the reduction of cell-to-cell communication in transformation is a possible primary effect of pp60src phosphorylation or secondary to a cytoskeletal alteration, we examined the junctional permeability in transformed cells with normal cytoskeleton. The permeability to fluorescent-labelled mono- and diglutamate was compared in clones of Faras' vole cells--clones transformed by Rous sarcoma virus and reverted from that transformation. One revertant clone (partial revertant), had the high level of pp60src kinase activity and tumorigenicity of the fully transformed parent clone, but had lost the cytoskeletal alterations of that clone. Another revertant clone (full revertant) had lost the tumorigenicity and most of the pp60src kinase activity, in addition (J.F. Nawrocki et al., 1984, Mol. Cell Biol. 4:212). The junctional permeability of the partial revertant with normal cytoskeleton was similar to that of the fully transformed parent clone with abnormal cytoskeleton. The permeabilities of both were lower than those of the full revertant and the normal uninfected cell, demonstrating that the junctional change by the src gene is independent of the cytoskeletal one.

Animals↗
PubMed1977

In vitro translation yields a possible Rous sarcoma virus src gene product.

In vitro translation of Rous sarcoma virus (RSV) virion RNA in the messenger-dependent reticulocyte lysate system yielded polypeptides that were not synthesized by translation of RNA from a transformation-defective deletion mutant of RSV. These RSV-specific products migrated on sodium dodecyl sulfate/polyacrylamide gels as two doublets of approximately 25,000 and 17,000 daltons. Synthesis of these proteins was not sensitive to inhibition by m7GTP; however, synthesis of the 76,000-dalton precursor of the internal structural proteins was sensitive to inhibition by m7GTP. Tryptic peptide maps showed the 25,000- and 17,000-dalton proteins to be related to one another but to be distinct from the 76,000-dalton protein. The 25,000-dalton protein was translated only from a polyadenylylated RNA of approximately 2500 nucleotides, whereas the 76,000-dalton protein was translated from 38S RNA, corresponding to the entire viral genome. A 180,000-dalton protein was also synthesized from 38S RSV virion RNA. From the absence of the 25,000- and 17,000-dalton proteins in the translation products of transformation-defective RSV RNA and the size of their RNA templates, we conclude that these proteins may be derived from coding sequences within the RSV src gene.

Animals↗
PubMed1991

Modulation of retinal differentiation by oncogenes: effect of the v-src gene on expression of choline acetyltransferase and glutamine synthetase.

Expression of the protooncogene c-src in chick neural retina is developmentally regulated and associated with neural differentiation. In the present study, chick neural retina (NR) cell cultures from 7 day embryos were exposed to the exogenous src oncogene, the c-src counterpart, to establish the effect of expression of v-src on specific retinal cellular differentiation. NR cells from 7 day chick embryos were placed in monolayer or rotation culture and infected with Rous sarcoma virus (RSV) containing a single transforming gene. Other cultures were infected with a transforming defective mutant of RSV which still possesses mitogenic activity for NR cells. While control cultures showed typical neuronal and Muller cell morphologies at the light and electron microscopic level, NR cells infected with RSV exhibited dramatic morphological alterations in monolayer culture and cell aggregates. However, the mutant src gene induced mitosis without accompanying transforming properties. When aggregate cultures were treated with hydrocortisone to induce glutamine synthetase (GS) expression in Muller cells, control cultures showed the typical immunofluorescence pattern of GS staining, while RSV infected cultures showed no GS fluorescence. Cultures infected with mutant RSV showed some staining for GS. In contrast, choline acetyltransferase activity was shown to increase in both monolayer and aggregate cultures of retinal cells following v-src expression. These data indicate that the presence of excess v-src in differentiating cultures of NR inhibits the expression of some neural specific enzymes and enhances the presence of other specific proteins. Moreover, continually growing cultures of oncogene-altered retinal cells may be useful as models to study gene expression in development of the nervous system.

Animals↗
PubMed1993

Ras1-dependent signaling by ectopically-expressed Drosophila src gene product in the embryo and developing eye.

The cellular functions of the Drosophila src 64B (Dsrc) gene product, Dsrc, and of most vertebrate Src-family kinases, are unknown. We have examined the effects of over-expression of wild type and mutated forms of Dsrc in transgenic Drosophila. Expression of both wild type Dsrc and a C-terminally truncated mutant at high levels during embryonic development induced extensive tyrosine phosphorylation of cellular proteins and caused considerable lethality, correlating with a block to germ-band retraction. Over-expression in the eye imaginal disc led to excess production of photoreceptor cells in the adult ommatidia. In contrast, expression of a kinase-inactive form of Dsrc caused distinct nervous system abnormalities in embryos and decreased the numbers of photoreceptor cells in the adult eye ommatidia. This suggests that active forms of Dsrc alter development by phosphorylation. Both the lethality and the eye roughening caused by activated Dsrc were partially suppressed by mutations in the Drosophila Ras1 gene. These results suggest that over-expressed Dsrc may function through Ras1 to stimulate differentiation in the embryonic nervous system and eye imaginal disc, and that kinase-active Dsrc interferes with these processes.

Animals↗
PubMed1994

The 3' region of c-src gene mRNA is entirely included in exon 12 and does not encode another protein.

We previously reported the isolation of PR2257, a novel replication defective avian sarcoma virus which transduced the entire c-src coding region together with about 900 bp of c-src 3' non coding sequences. This virus originated from a chicken sarcoma induced by inoculation of a transformation-defective Rous sarcoma virus carrying only replicative genes. The 5' end of PR2257 was formed by a splice junction between viral leader sequences and the first exon of c-src. To understand the mechanism of 3' recombination between viral and cellular sequences, we analyzed the genomic organization of the 3' region in chicken and quail src DNA. We report that this sequence is colinear with that of a chicken src cDNA. Therefore, exon 12, which encodes the last 68 amino acids of c-src, also contains all 3' non coding sequences present in c-src mRNA and consequently, appears to be the last and largest (about 2 kbp) exon of c-src. We also show that the 3' regions of chicken and quail c-src genes does not contain the additional open reading frame (orf) which was previously reported (Dorai et al. (1991) Mol. Cell. Biol. 11, 4165-4176), and that no other significant conserved open reading frames could be found in this region for both species. Therefore, this region of src does not code for another protein. Taken together, our results suggest that PR2257 was generated by recombination at the RNA level. However, because of the absence of introns in this region of c-src, we cannot formally rule out the possibility that this recombination took place at the DNA level.

Animals↗