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 649 records · Page 36Linked to original sources
PubMed1981

F-actin aggregates in transformed cells.

Polymerized actin has been found aggregated into distinctive patches inside transformed cells in culture. The F-actin-specific fluorescent probe, nitrobenzoxadiazole-phallacidin, labels these F-actin aggregates near the ventral cell surface of cells transformed by RNA or DNA tumor viruses, or by chemical mutagens, or spontaneously. Their appearance in all eight transformed cell types studied suggests their ubiquity and involvement in transformation morphology. Actin patches developed in normal rat kidney (NRK) cells transformed by a temperature-sensitive mutant of Rous sarcoma virus (LA23-NRK) within 30 min after a shift from the nonpermissive (39 degrees C) to the permissive temperature (32 degrees C). Patch appearance paralleling viral src gene expression tends to implicate pp60src kinase activity in destabilizing the cytoskeleton. However, appearance of the actin aggregates in cells not transformed by retrovirus calls for alternative mechanisms, perhaps involving an endogenous kinase, for this apparently common trait.

Actins↗
PubMed1999

Inhibition of human immunodeficiency virus type 1 by Tat/Rev-regulated expression of cytosine deaminase, interferon alpha2, or diphtheria toxin compared with inhibition by transdominant Rev.

A retroviral vector was designed to express toxic proteins only in the presence of the HIV-1 Rev and/or Tat protein(s). The design of this vector incorporates an HIV-specific expression cassette that consists of three elements: the U3R region of the HIV-1 IIIB LTR provides the promoter and Tat-responsive element, a modified intron derived from the human c-src gene facilitates the splicing of inserted genes, and the HIV-1 RRE region enhances the transport of unspliced mRNAs. To further limit potential readthrough transcription, the expression cassette was inserted in the reverse transcriptional orientation relative to the retroviral vector LTR. Three different genes, interferon alpha2, diphtheria toxin (DT-A), and cytosine deaminase, were inserted into this vector. Tat and Rev inducibility was demonstrated directly by a >300-fold induction of interferon production and functionally by a decrease in colony-forming units when a Tat and Rev expression vector was titered on HeLa cells harboring the inducible DT-A cassette. The Tat-inducible cytosine deaminase gene was tested in the Sup-T1 T cell line and shown to inhibit HIV-1 production only when engineered cells were grown in the presence of 5-fluorocytosine. To test the ability of this system to inhibit HIV-1 infection in bulk PBL cultures, a series of transduction and challenge experiments was initiated with both the interferon and DT-A vectors. Protection against infection was documented against three HIV strains in PBLs. Last, the interferon and DT-A vectors were compared with a vector encoding a transdominant Rev protein and were shown to mediate equal or greater inhibition of HIV-1.

Blotting, Northern↗
PubMed1979

Inhibition of spontaneous transformation of rat embryo cells releasing endogenous type C virus by virus-specific antiserum.

Noninbred Sprague-Dawley rat embryo cell clones predictably undergo transformation after 20-30 in vitro passages following spontaneous release of endogenous rat leukemia virus (RaLV). In the presence of RaLV-specific antiserum, virus production and infectivity were reduced and transformation was delayed from 6 to 25 weeks. Transformation was not associated with an increased expression of Kirsten murine sarcoma virus-related src gene RNA.

Animals↗
PubMed1982

Structure-function relationship of Rous sarcoma virus leader RNA.

Cells infected by RSV synthesize viral 35S RNA as well as subgenomic 28S and 22S RNAs coding for the Env and Src genes respectively. In addition, at least the 5' 101 nucleotides of the leader are also conserved and we have shown previously that this sequence contains a strong ribosome binding site (J.-L. Darlix et al., J. Virol. 29, 597). We now report the RNA sequence of Rous Sarcoma virus (RSV) leader RNA and propose a folding of this 5' untranslated region which brings the Cap, the initiation codon for Gag and the strong ribosome binding site close to each other. We also show that ribosomes protect a sequence just upstream from initiator Aug of Gag in vitro, and believed to interact with part of the strong ribosome binding site according to the folding proposed for the leader RNA.

Animals↗
PubMed1983

High spontaneous mutation rate of Rous sarcoma virus demonstrated by direct sequencing of the RNA genome.

Direct and extensive sequencing of RSV RNA genome is reported. More than 10,000 nt of the T1 RNase resistant RSV RNA fragments (1) have been sequenced and shown to cover 3900 nt of RSV genome. The frequent sequence variations found indicate that RSV supports a very high incidence of spontaneous mutations in the course of replication, one very probable cause of the genetic diversity among the avian retroviruses. Sequences of the structured RSV RNAs allowed us also to precisely characterize the structured domains of the retroviral genome and show that the src gene is not structured.

Amino Acid Sequence↗
PubMed1984

Analysis of the variations in proviral cytosine methylation that accompany transformation and morphological reversion in a line of Rous sarcoma virus-infected Rat-1 cells.

Cells of the A11 lineage of Rat-1 contain a single complete Rous sarcoma provirus. Variation in the activity of this provirus accompanies fluctuations in the lineage between normal and transformed phenotypes. Increased proviral cytosine methylation of the doublet CpG in the tetranucleotide CCGG correlates with transcriptional inactivity and this pattern of cytosine hypermethylation is stable, even when the cells are transformed by another virus. However, transformation can also be induced by 5-azacytidine (but not by other mutagens) and in these transformants reduced proviral cytosine methylation is accompanied by increased proviral transcription. Differences in CCGG methylation between normal and transformed cells are found mainly in the 3' half of the provirus; sites near and within the src gene are heavily methylated only when the provirus is transcriptionally inactive. On the other hand, both transformed and normal A11 derivatives show little, if any, cytosine methylation of CCGG sequences in and flanking the 5' portion of the provirus.

5-Methylcytosine↗
PubMed1980

Fine structure mapping of an avian tumor virus RNA by immunoelectron microscopy.

The RNA of a deleted strain (lacking Src gene) of an avian sarcoma virus (ASV) was examined by a newly developed immunoelectron microscopic procedure which uses anti-nucleotide antibodies as probes. After denaturation of the RNA and reaction with a high affinity, highly specific anti-7-methylguanosine-5'-phosphate (anti-pm 7G), 81% of 106 molecules examined were found to have antibody at one terminus, in agreement with the presence of a pm 7G cap in ASV-RNA. Hapten inhibition by pm 7G could be demonstrated. Experiments with anti-A and with anti-poly A gave results consistent with the known structure of ASV-RNA, in particular the presence of a 3' poly A tail. These studies illustrate the feasibility of using anti-nucleotide antibodies in a combined immunochemical and electron microscopic study of the fine structure of nucleic acids.

Alpharetrovirus↗
PubMed1985

How do retroviral oncogenes induce transformation in avian erythroid cells?

The v-erb B oncogene, as well as other oncogenes of the src-gene family transform immature erythroid cells from chick bone marrow in vivo and in vitro. The erb B-transformed erythroid cells differ from normal late erythroid precursors (CFU-E) in that they have acquired the capacity to undergo self-renewal as well as to differentiate terminally. They also do not require the normal erythroid differentiation hormone, erythropoietin, for either process. Cooperation of v-erb B with a second oncogene, v-erb A, results in a differentiation arrest of the transformed cells, which now only use the self-renewal pathway. Studies with conditional and non-conditional mutants in both v-erb B and v-erb A will be presented to elucidate further how the transforming proteins encoded by these oncogenes, gp74erb B and gp75gag-erb A, affect the differentiation programme of the infected erythroid precursor with the outcome of hormone-independent leukaemic cells arrested at an early stage of erythroid differentiation.

Animals↗
PubMed1980

Transformation of NIH-3T3 mouse cells by avian retroviral DNAs.

NIH-3T3 cells were found to be transformable by RSV DNA in the absence of progeny virus production. Cells transformed by intact RSV DNAs contained rescuable RSV genomes that were integrated into cellular DNA and were colinear with unintegrated RSV DNA. NIH-3T3 cells were also transformable by subgenomic fragments of RSV DNA, synthesized in vitro or generated by restriction endonuclease digestion of intracellular RSV DNA. These cells did not contain rescuable RSV genomes but did contain RSV DNA fragments that efficiently induced transformation of NIH-3T3 cells in secondary transfection assays. Further analysis of the RSV DNA sequences present in these cells and transformation assays of defined fragments of RSV DNA may contribute to the elucidation of the sequences required for expression of the src gene of RSV. DNAs of the avian acute leukemia viruses MC29 and AEV also induced transformation of NIH-3T3 cells. The use of these cells as recipients may thus provide a system suitable for functional analysis of the transforming genes of avian leukemia viruses as well as sarcoma viruses.

Animals↗
PubMed1991

Epigenetic control of tumor cell morphology.

XC cell line derived from a single rat cell transformed by the Prague strain of Rous sarcoma virus produced morphologically different colonies. Among them, two distinct cell types consisting of thick, fusiform cells (L-type), and of flat, polygonal cells (R-type) were apparent. By repeated subclonings, pure cultures, L1 and R1, respectively, were obtained. These clones underwent morphological conversion during prolonged culture; L-type colonies appeared in the R-type clone and vice versa. The kinetic curve suggested that the conversion was multi-stepped. When inoculated into nude mice, L-type cells produced much larger tumors at a higher frequency than R-type cells, and the tumors induced by these two clones were histologically different. The expression of v-src gene was higher in L-type than in R-type cells at both mRNA and protein levels.

Actins↗
PubMed1994

Differentiation of a Ewing's sarcoma cell line towards neural and mesenchymal cell lineages.

Two different pathways of differentiation were investigated in Ewing's sarcoma (ES) cell line, designated CADO-ES1, which has been established in our laboratory. This cell line was induced to differentiate and display a neural phenotype when treated with dibutyryl cyclic adenosine monophosphate or when cultured in serum-free medium (HB101). In these in vitro differentiation studies, two different phenotypes were demonstrated by light and electron microscopy. One phenotype, present in a major portion of the cell population, had long neurites in which microtubules were ultrastructurally demonstrated. The other one, present in a minor portion of the cell population, consisted of flat cells with many short processes. After differentiation in serum-free medium, tumorigenicity in nude mice or colony-forming efficiency in soft agar was strongly depressed. In the cells, N-myc, c-fos and c-src genes were not amplified, and although c-myc was amplified by up to 2-fold, depending on the culture conditions, this appeared to be unrelated to the changes of phenotype. When tumor cells were transplanted into nude mice, cartilage was formed. The cartilage was immunoreactive with the antibody for HLA-ABC, indicating that it was derived from the tumor cells, not from mouse tissue.

Animals↗
PubMed1980

Simultaneous decrease in deamination of 5'-adenylic acid and 5'-deoxy-5'-S-isobutylthioadenosine in chick-embryo fibroblasts infected by Rous sarcoma virus.

The rate of deamination of 5'-deoxy-5'-S-isobutylthioadenosine [(iBuS5'Ado] in chick embryo fibroblasts was substantially reduced after their infection and morphological transformation by Rous sarcoma virus. Concomitant with the reduction in rate of (iBuS)5'Ado deamination there was a decrease in adenosine deaminase and 5'-adenylic acid deaminase activities. The drop of these activities was related to infection and not to the expression of the src gene. (iBuS)5'Ado was deaminated by at least three enzymes or isoenzymes whose apparent molecular weights have been estimated to be 295000, 121000 and 37000 respectively. Two of these enzymes have been characterized as 5'-adenylic acid deaminase and the heavy form of adenosine deaminase, respectively.

Adenosine Deaminase↗
PubMed1985

Fractionation by high-performance liquid chromatography of the low-molecular-mass high-mobility-group (HMG) chromosomal proteins present in proliferating rat cells and an investigation of the HMG proteins present in virus transformed cells.

The low-molecular-mass high-mobility-group (HMG) proteins from young rat thymus nuclei were fractionated by high-performance liquid chromatography. Two proteins analogous to calf HMG14 and HMG17 were found together with a third major component HMGI similar to that found in HeLa cells [Lund et al. (1983) FEBS Lett. 152, 163-167]. HMGI has as amino acid composition similar to but distinct from HMG14 and HMG17. The three proteins form a family of proteins with HMG14 having an amino acid composition intermediate between HMG17 and HMGI. HMGI is present in proliferating fibroblasts and embryos but is present in very low levels in rat liver, a non-dividing tissue, supporting the notion that HMGI is required for proliferating cells. Fibroblasts transformed with avian sarcoma virus have high levels of HMGI and an additional band HMGI' but the presence of HMGI and HMGI' is not dependent on a functional src gene product.

Amino Acids↗
PubMed1995

Porphyromonas gingivalis fimbria-stimulated bone resorption in vitro is inhibited by a tyrosine kinase inhibitor.

Our previous study (Y. Kawata, S. Hanazawa, S. Amano, Y. Murakami, T. Matsumoto, K. Nishida, and S. Kitano, Infect. Immun. 62:3012-3016, 1994) showed that Porphyromonas gingivalis fimbriae stimulate bone resorption in vitro. Since it has recently been demonstrated that tyrosine kinase encoded by the c-src gene plays an important role in osteoclastic bone resorption, in the present study we examined the effect of a tyrosine kinase inhibitor on the fimbria-stimulated bone resorption. Genistein, a potent inhibitor of tyrosine kinase, markedly inhibited bone resorption stimulated by the fimbriae. Genistein also inhibited induction of several tyrosine-phosphorylated proteins in the fimbria-treated calvarial bone cells from mouse embryos.

Animals↗
PubMed1978

Nucleotide sequence relationships between the genomes of an endogenous and an exogenous avian tumor virus.

We have used mapping of large T1 oligonucleotides to examine the genome of Rous-associated virus-O (RAV-O), an endogenous virus of chickens, and to compare it with that of Prague strain Rous sarcoma virus, subgroup B, (Pr-RSV-B), an exogenous sarcoma virus. To extend the sensitivity of such comparisons, we have developed a system of nucleic acid hybridization and hybridization-competition combined with fingerprinting. This method allows us to estimate the relative degree of relatedness of various portions of the viral genomes. From the results of this study, we have concluded that the genomes of Pr-RSV-B and RAV-O are related in the following way. The 5'-terminal half of the genomes (corresponding to the gag and pol regions) is virtually identical, with only scattered single nucleotide differences. This region is followed by a region comprising 25 to 30% of the genome (the env region) which contains substantial nucleotide sequence differences, most or all of which are due to single base changes. The env-coding region can be further subdivided into three regions: a more variable region probably containing sequences coding for subgroup specificity, flanked by relatively common sequences on each side. To the 3' side of the env region, the RAV-O genome contains a very short sequence not found in Pr-RSV-B, whereas the Pr-RSV-B genome contains a much longer unrelated sequence. The central portion of this sequence comprises the src gene as defined by transformation-defective mutants. Particularly striking is the absence, in the RAV-O genome, of any nucleotide sequence related to the "c region" found very near the 3' end of all exogenous tumor viruses. Both the Pr-RSV-B and RAV-O genomes contain the identical terminally redundant sequence of 21 nucleotides near each end of the genome.

Avian Leukosis Virus↗
PubMed1979

Polymorphism of avian sarcoma virus src proteins.

The src gene products of seven different avian sarcoma viruses were compared. In vitro translation of virion RNA yielded products identified unambiguously as p60src in the case of two stocks of the Schmidt-Ruppin strain, three stocks of the Prague strain, the Bryan strain, and the Bratislava 77 strain of avian sarcoma virus. Differences in the electrophoretic mobility of these seven p60src proteins in sodium dodecyl sulfate-polyacrylamide gels, corresponding to variation in the apparent molecular weights ranging from 56,000 to 60,500, were observed. Antigenic variability was also found; only three of the seven viruses tested encoded a p60src, which was precipitated by antisera derived from rabbits bearing tumors induced by the Schmidt-Ruppin strain of Rous sarcoma virus. Examination of the methionine-containing tryptic peptides of the seven ;60src proteins by two-dimensional mapping revealed four common peptides but marked variability in the five to eight other peptides in each protein. Clear differences in the peptide maps of p60src were observed, both between different strains of virus and within strains. In the three cases examined, p60src synthesized in transformed cells was found to be essentially identical to that synthesized in vitro. We conclude that there is significant polymorphism in the p60src proteins of the avian sarcoma viruses.

Avian Sarcoma Viruses↗
PubMed1979

Suppression of multiplication of avian sarcoma virus by rapid spread of transformation-defective virus of the same subgroup.

We have tested the hypothesis that some transformation-defective (td) viruses grow faster than the avian sarcoma viruses (ASV) from which they are derived, resulting in establishment of interference by the td virus and suppression of the ASV multiplication. Using an ASV of subgroup A (ASV-A) that does not contain td virus and an independently isolated tdASV-A, we performed separate and mixed infections to test this hypothesis. At multiplicities of 1 or less, tdASV alone grew to higher titers and more rapidly than ASV alone. In mixed infections at low multiplicities that allowed spread of progeny virus, when as little as 10% of the virus inoculum was td virus, there was an excess of td virus by 2 days after infection and a decrease in the titer of ASV relative to a control infection with no td virus. In mixed infections at high multiplicities which minimized spread of progeny virus, there was no excess of td virus and the titer of ASV was not decreased relative to the control infection with no td virus. These data support the hypothesis that we proposed and indicate that deletions in the ASV src gene may not be a high-frequency event. We also present data concerning the amounts of unintegrated viral DNA found after the separare and mixed infections. There was no simple correlation between the amounts of unintegrated viral DNA early after infection and the titers of virus produced, indicating perhaps that virus production was determined by integrated viral DNA.

Animals↗
PubMed1979

Characterization of an immune complex kinase in immunoprecipitates of avian sarcoma virus-transformed fibroblasts.

Kinase activity detected in immune complexes containing the src gene product of the avian sarcoma virus has been reported. To further characterize this immune complex kinase, we developed a routine quantitative assay involving trichloroacetic acid precipitation on filters. The enzyme reaction required either Mg2+ or Mn2+, but was inactive with Ca2+. The kinetics of the phosphorylation reaction indicated a transient enzyme activity limited by rapid substrate-dependent inactivation of the enzyme. A variety of nucleoside and deoxyribonucleoside triphosphates (dATP, ATP, GTP, CTP, dGTP, TTP, dCTP) served as phosphoryl donors. The phosphorylation of immunoglobulin G was inhibited by the presence of nucleoside diphosphates. Deoxyribonucleoside diphosphates can either stimulate or inhibit the kinase reaction depending upon the concentration used. The unusual enzymatic properties of the immune complex kinase raise the possibility that the enzyme does not function as a protein kinase in vivo, but rather belongs to a different class of kinases (nucleotide kinases) which adventitiously phosphorylates immunoglobulin G when immunoprecipitated with immune serum.

Animals↗