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B Mathey-Prevot

Publications and source records attributed to B Mathey-Prevot.

34 records · Page 2Linked to original sources
PubMed1991

Preneoplastic lesions induced by myc and src oncogenes in a heterotopic rat colon.

With the use of viral vectors harboring myc and src oncogenes, we have assessed the potential contribution of these different elements to colonic neoplasia using a transplantation technique resulting in the formation of a heterotopic colon in Wistar Furth rats. While myc alone induced atypia and some dysplasia, src induced focal dysplastic lesions throughout the colon mucosa with evidence of metaplasia. In contrast, lesions induced by myc and src acting cooperatively, were highly dysplastic with evidence of tumor formation after protracted periods. These results indicated the formation of histologically distinct preneoplastic lesions elicited by the action of a single oncogene in colon implants with the production of adenocarcinomas when such oncogenic elements act cooperatively. This model provides an opportunity for studies of the action of different oncogenes, acting singly or in combination, in the multi-step progression to colon tumor formation.

Animals↗
PubMed1990

Positive and negative elements regulate human interleukin 3 expression.

The human interleukin 3 (IL-3) promoter is comprised of several cis-acting DNA sequences that modulate T-cell expression of IL-3. These are located within 315 nucleotides upstream of the mRNA start site. Transient expression of reporter genes linked to serially deleted sequences of the IL-3 promoter has allowed mapping of two activator sequences and an interposed repressor sequence. The proximal regulatory region is specific to IL-3 and prerequisite for efficient transcription. Its effect is enhanced by a second, more distal activating sequence consisting of an AP-1 binding site. Between the two activators lies a transcriptional silencer, which is a potent repressor in the absence of the AP-1 site. DNA-nuclear protein binding experiments demonstrate specific complex formation within each of these functional regions. Thus, both positive and negative regulatory elements appear to control expression of the human IL-3 gene in activated T cells.

Base Sequence↗
PubMed1989

Expression of human interleukin-3 (multi-CSF) is restricted to human lymphocytes and T-cell tumor lines.

While the cellular sources for granulocyte-macrophage colony-stimulating factor (GM-CSF) are known to be widely distributed among several cell types, interleukin-3 (IL-3) gene expression has been demonstrated in only certain T-cell clones and in blood mononuclear cells stimulated with phytohemagglutinin (PHA) and phorbol-myristate-acetate (PMA). To determine which blood cells were responsible for this expression, we fractionated PHA/PMA-stimulated mononuclear cells and identified T lymphocytes as the source of IL-3 mRNA. Low-level IL-3 expression was detected as well in several stimulated human T-cell lines. Hematopoietic stromal cells such as fibroblasts and endothelial cells could not be induced to express IL-3 mRNA. The kinetics of IL-3 mRNA induction in mononuclear cells and lymphocytes stimulated with PHA/PMA or anti-CD3 monoclonal antibody (MoAb) and interleukin-1 (IL-1) were similar to those observed for GM-CSF expression.

Colony-Stimulating Factors↗
PubMed1989

Granulocyte-macrophage colony-stimulating factor and interleukin-3 mRNAs are produced by a small fraction of blood mononuclear cells.

Northern blot analysis has identified granulocyte macrophage colony stimulating factor (GM-CSF) mRNA in monocytes and both GM-CSF and interleukin-3 (IL-3) mRNA in lymphocytes. However, these results have not addressed whether all cells or a subset of the population is capable of hematopoietic growth factor (HGF) production. To resolve this question, we applied in situ hybridization of radiolabeled antisense RNA probes to centrifuged preparations of total blood mononuclear cells (BMCs) and fractionated lymphocyte subpopulations. Without stimulation, no circulating cells expressed detectable levels of GM-CSF or IL-3 mRNA. On stimulation of BMCs with phorbol myristate acetate (PMA) and phytohemagglutinin or PMA and the calcium ionophore ionomycin, approximately 5% expressed GM-CSF mRNA and approximately 1% IL-3 mRNA. Control sense probes produced no labeled cells. To determine the subsets of lymphocytes capable of GM-CSF and IL-3 expression, BMCs were fractionated by FACS into CD8+ and CD4+ lymphocyte subsets and CD16+ (NK) cells. The unfractionated cells and cell fractions were then stimulated with PMA and ionomycin. Results demonstrated that 3% to 5% of the CD16+, CD8+, and CD4+ lymphocytes produced GM-CSF mRNA. However, the number of IL-3 mRNA-positive cells in the FACS-sorted subsets was greatly reduced (0.02% to 0.05%) as compared with the unseparated cells (1%). Treatment of BMCs with high-dose interleukin-2 (IL-2) for 1 week followed by PMA plus ionomycin resulted in a lymphocyte population in which 50% and 3% of cells expressed GM-CSF and IL-3 mRNA, respectively. Thus, GM-CSF and IL-3 mRNA expression in T cells and NK cells is restricted to a small fraction of cells that can be greatly expanded by IL-2 stimulation. These results suggest a possible physiologic mechanism for increasing HGF production by circulating lymphocytes.

Blotting, Northern↗
PubMed1988

A human immunoglobulin gene reduces the incidence of lymphomas in c-Myc-bearing transgenic mice.

Transgenic mice carrying an immunoglobulin enhancer-driven c-myc oncogene develop rapid-onset pre-B cell lymphomas. The incidence of these malignancies is greatly reduced when an additional transgene encoding the membrane-bound form (but not the secreted form) of human Ig mu is bred into the susceptible strain. This suppressive effect correlates with a subtle alteration in B-cell development induced by the immunoglobulin transgene.

Abelson murine leukemia virus↗
PubMed1988

Recombinants within the tyrosine kinase region of v-abl and v-src identify a v-abl segment that confers lymphoid specificity.

The v-abl and v-src oncogenes encode protein-tyrosine kinases that possess different biological properties in spite of their high degree of amino acid conservation. To correlate functional differences with structural domains of the two oncogenes, we recombined v-abl and v-src just downstream of the lysines in their ATP-binding sites, within the kinase domain. The biological activity of the chimeric genes was studied and compared with that of v-src and v-abl. The v-src/v-abl recombinant shared with v-src and v-abl the ability to transform fibroblasts. In addition, like v-abl, it transformed lymphoid cells and relieved a hematopoietic cell line of its interleukin 3 requirement. In contrast, the reciprocal construct, v-abl/v-src, was transformation defective. Lack of biological activity correlated with formation of a stable complex between the chimeric protein and two cellular proteins and with low kinase activity. We conclude that the specificity within the kinase domain determines the particular biological behavior of protein-tyrosine kinase oncogenes.

Cell Transformation, Neoplastic↗
PubMed1987

Neuronal pp60c-src contains a six-amino acid insertion relative to its non-neuronal counterpart.

Neuronal cells express a pp60c-src variant that displays an altered electrophoretic mobility and a different V8 peptide pattern relative to pp60c-src expressed in tissues of non-neuronal origin. To determine whether the neuronal form of pp60c-src is encoded by a brain-specific messenger RNA, a mouse brain complementary DNA (cDNA) library was screened with a chicken c-src probe and a 3.8-kilobase c-src cDNA clone was isolated. This clone encodes a 60-kilodalton protein that differs from chicken or human pp60c-src primarily in having six extra amino acids (Arg-Lys-Val-Asp-Val-Arg) within the NH2-terminal 16 kilodaltons of the molecule. S1 nuclease protection analysis confirmed that brain c-src RNA contains an 18-nucleotide insertion at the position of the extra six amino acids. This insertion occurs at a position that corresponds to a splice junction in the chicken and human c-src genes. The isolated c-src cDNA clone encodes a protein that displays an identical V8 peptide pattern to that observed in pp60c-src isolated from tissues of neuronal origin.

Amino Acid Sequence↗
PubMed1986

Abelson virus abrogation of interleukin-3 dependence in a lymphoid cell line.

Among several tyrosine-protein kinases, only v-abl could abrogate interleukin 3 dependence of a lymphoblastoid cell line; v-src and v-fps proteins gave partial or no interleukin 3 independence, respectively. Lymphokine independence was achieved via a nonautocrine mechanism. Direct involvement of c-myc in this process was not evident.

Abelson murine leukemia virus↗
PubMed1985

Specific transforming potential of oncogenes encoding protein-tyrosine kinases.

Several chimeric murine retroviruses were constructed to test whether the gag sequence of Abelson murine leukemia virus (A-MuLV) could influence the in vitro specificity of two sarcoma-inducing oncogenes: src of Rous sarcoma virus and fps of Fujinami sarcoma virus. Although the src- or fps- containing chimerae could transform fibroblasts, they were unable to mimic the action of A-MuLV in causing lymphoid transformation in vitro. A-MuLV-derived gag sequences could, however, functionally replace the 5' end of src and restore the transformation potential of a 5'-truncated src gene. To investigate this functional similarity, we replaced the gag sequence of an A-MuLV virus with the 5' end of src. This recombinant virus behaved like the A-MuLV virus from which it was derived: it transformed both fibroblasts and lymphoid cells in vitro. Taken together, these results suggest that lymphoid transformation in vitro is a specific property of abl and not of src or fps. Furthermore, it shows that a functional homology exists between the gag sequence of A-MuLV and the 5' end of src.

Abelson murine leukemia virus↗
PubMed1985

Preferential expression of the c-fps protein in chicken macrophages and granulocytic cells.

We have studied the expression of the protein kinase activity of NCP98, the c-fps gene product, in several hemopoietic tissues of chickens as a function of the developmental stage of these organs. We found that in bone marrow, spleen, and bursa, maximum NCP98 kinase activity on a per-cell basis correlates with the peak of granulopoiesis in these organs. Furthermore, in a bovine serum albumin density gradient fractionation of bone marrow cells, granulocytic cells appeared to account for most of the NCP98 kinase activity. No correlation was found between the distribution of erythrocytic, lymphocytic, or thrombocytic cells and the distribution of the expression of NCP98 kinase activity. However, NCP98 protein and kinase activity were 10-fold higher in macrophages than in bone marrow. In addition, depletion by complement-mediated lysis of erythrocytic cells in bone marrow did not significantly reduce the total recovery of NCP98 kinase activity. These results argue for the specific expression of the c-fps gene product in granulocytic cells and macrophages.

Animals↗
PubMed1984

Revertants and partial transformants of rat fibroblasts infected with Fujinami sarcoma virus.

Fifteen revertants were isolated from three independent clones of rat fibroblasts transformed by Fujinami sarcoma virus (FSV). Three revertant clones resulted from the deletion of the one copy of the FSV provirus, and one encoded an enzymatically inactive, transformation-defective protein. The remaining revertant clones were characterized by a transcriptional block of the provirus. Digestion of chromosomal DNA with MspI and HpaII revealed that the FSV provirus was hypermethylated in these revertants, whereas proviral DNA of their spontaneous retransformants was hypomethylated. Furthermore, the revertants had lost DNase I-hypersensitive sites in and around the FSV provirus. The effect of transcriptional regulation of the FSV provirus was further analyzed in clones showing various degrees of phenotypic transformation. We quantitated v-fps mRNA levels in these cells by liquid hybridization and found that increasing levels of viral RNA correlated with a more pronounced transformed phenotype. These results suggest that transcription of FSV proviral DNA is under both viral and cellular control and that transformation by FSV is a function of the dosage of v-fps mRNA.

Animals↗
PubMed1982

A cellular protein is immunologically crossreactive with and functionally homologous to the Fujinami sarcoma virus transforming protein.

We obtained a regressing-tumor antiserum specific for the unique sequence of the transforming protein P140 of Fujinami sarcoma virus by injecting Fischer rats with syngeneic embryo cells transformed with Fujinami sarcoma virus. This serum is capable of immunoprecipitating a protein of 98,000 daltons from cell extracts of normal, uninfected chicken bone marrow cells. This normal cellular protein (NCP98) was shown to be structurally related to P140, sharing the majority of 35S-methionine-labeled tryptic peptides with the viral gene product P140. NCP98 is a phosphoprotein in vivo, with an associated in vitro protein kinase activity, capable of phosphorylating specifically at tyrosine residues of NCP98 itself and alpha-casein, an externally added substrate. This kinase activity is biochemically indistinguishable from the kinase activity associated with P140 by all criteria tested. Moreover, in vitro-phosphorylated NCP98 and P140 shared the same phosphopeptides. The expression of NCP98 is tissue-specific. It is readily detectable in bone marrow cells and detectable to a lesser extent in liver and lung cells from 6--18 day old chickens.

Animals↗
PubMed1982

Isolation of 16L virus: a rapidly transforming sarcoma virus from an avian leukosis virus-induced sarcoma.

We have isolated a replication-defective rapidly transforming sarcoma virus (designated 16L virus) from a fibro-sarcoma in a chicken infected with td107A, a transformation-defective deletion mutant of subgroup A Schmidt-Ruppin Rous sarcoma virus. 16L virus transforms fibroblasts and causes sarcomas in infected chickens within 2 wk. Its genomic RNA is 6.0 kilobases and contains sequences homologous to the transforming gene (fps) of Fujinami sarcoma virus (FSV). RNase T1 oligonucleotide analysis shows that the 5' and 3' terminal sequences of 16L virus are indistinguishable from (and presumably derived from) td107A RNA. The central part of 16L viral RNA consists of fps-related sequences. These oligonucleotides fall into four classes: (i) oligonucleotides common to the putative transforming regions of FSV and another fps-containing avian sarcoma virus, UR1; (ii) an oligonucleotide also present in FSV but not in UR1; (iii) an oligonucleotide also present in UR1 but not in FSV; and (iv) an oligonucleotide not present in either FSV, UR1, or td107A. Cells infected with 16L virus synthesize a protein of Mr 142,000 that is immunoprecipitated with anti-gag antiserum. This protein has protein kinase activity. These results suggest that 16L virus arose by recombination between td107A and the cellular fps gene.

Animals↗
PubMed1981

Mutants of Fujinami sarcoma virus which are temperature sensitive for cellular transformation and protein kinase activity.

Two temperature-sensitive mutants of Fujinami sarcoma virus were isolated and characterized. Cells infected with the mutants were temperature sensitive in focus formation, colony formation, increased sugar uptake, and synthesis of plasminogen activator. The changes between transformed and nontransformed states of cultures were completely reversible by shifting the temperature. A Fujinami sarcoma virus-specific protein of 130,000 daltons, p130, was synthesized in mutant-infected cells regardless of the temperature, but the immunoprecipitates of p130 from extracts of infected cells were active in protein kinase only when cells had been incubated at the permissive temperature. These results appear to indicate that p130 is the transforming protein of Fujinami sarcoma virus, and that its protein kinase activity plays a crucial role in cell transformation by this virus.

Alpharetrovirus↗
PubMed1980

Purification and chemical characterization of melittin and acetylated derivatives.

Melittin, the main basic and hydrophobic peptide of bee venom, displays marked detergent-like properties. At high peptide concentration, and depending on salt and pH, it forms a tetramer. This is prevented by using urea. A purification procedure in presence of 4.0 M urea was developed to prepare melittin in its monomeric form, free of other venom constituents such as N alpha-formyl melittin, degradation products of peptides and phospholipase A2. NH2-residues on the melittin molecule were modified by reaction with acetic anhydride to alter the asymmetrical charge distribution supposed to confer detergent-like properties to the molecule. This gave rise to di- and mono acetyl derivatives which could be used, once isolated, to study further the melittin structure-activity relationship.

Animals↗