Search PubMed⌕ Search

Biomedical subjects

J Ghysdael

Publications and source records attributed to J Ghysdael.

At least 109 records · Page 6Linked to original sources
PubMed1987

Multiple domains for the chicken cellular sequences homologous to the v-ets oncogene of the E26 retrovirus.

We have investigated the structure of chicken genomic DNA homologous to v-ets, the second cell-derived oncogene of avian retrovirus E26. We isolated a c-ets locus spanning ca. 30.0 kilobase pairs (kbp) in the chicken genome with homologies to 1,202 nucleotides (nt) of v-ets (total length, 1,508 nt) distributed in six clusters along 18.0 kbp of the cloned DNA. The 5'-distal part of v-ets (224 nt) was homologous to chicken cellular sequences contained upstream within a single 16.0-kbp EcoRI fragment as two typical exons but not found transcribed into the major 7.5-kb c-ets (or 4.0-kb c-myb) RNA species. Between these two v-ets-related cellular sequences we found ca 40.0 kbp of v-ets-unrelated DNA. Finally, the most 3' region of homology to v-ets in the cloned DNA was shown to consist of a truncated exon lacking the nucleotides coding for the 16 carboxy-terminal amino acids of the viral protein but colinear to one of the two human c-ets loci, c-ets-2.

Animals↗
PubMed1987

The human c-myc exon 1 product: preparation of antisera and analysis of its expression.

We investigated the coding capacity of the previously reported open reading frame (ORF) of the human c-myc exon 1. By in vitro translation assay, we found that exon 1 ORF was translated into a 20-kd protein (p20 protein). In order to obtain antisera raised against the p20 protein, we constructed a plasmid vector which expressed most of the exon 1 ORF as a 25-kd (P25) protein in Escherichia coli. Polyclonal antisera raised against this P25 protein specifically precipitated a chimeric protein which contained exon 1-related amino acid sequences. We used these antisera to test for the existence of an exon 1 product in human cells. In the human cell lines tested, these antisera have failed so far to detect any exon 1-related proteins. However, exon 1-related proteins were detected with the anti-p20 antisera in quail embryonic cells (QEC) transfected by human c-myc recombinants constructed to express such proteins, but were expressed at low levels compared with the human c-myc protein also expressed in the transfected QEC. Our results suggest that secondary structure of the mRNA could be responsible for the low expression of the exon 1 product in QEC.

Animals↗
PubMed1986

Expression of the v-src or v-fps oncogene increases fructose 2,6-bisphosphate in chick-embryo fibroblasts. Novel mechanism for the stimulation of glycolysis by retroviruses.

The concentration of fructose 2,6-bisphosphate and the activity of 6-phosphofructo-2-kinase are increased after infection of chick-embryo fibroblasts with the Rous sarcoma virus, or with a temperature-sensitive mutant of this virus at the permissive, but not at the non-permissive, temperature. This is observed after transformation by retroviruses carrying either the v-src or v-fps, but not the v-mil and/or v-myc, oncogenes. Comparison of the effects of the Rous sarcoma virus with those of phorbol myristate acetate on fructose 2,6-bisphosphate suggests that both result from the stimulation of a step which is rate-limiting for 6-phosphofructo-2-kinase activation and which is also controlled by protein kinase C.

Animals↗
PubMed1986

Transformation of quail embryo fibroblasts by a retrovirus carrying a normal human c-myc gene.

We have constructed avian retroviruses expressing the human c-myc oncogene. These viruses morphologically transformed primary quail embryo fibroblasts upon transfection and infection. Transformed cells produced viruses harboring a spliced c-myc gene and contained high levels of p64-67c-myc protein. One of these infectious viruses, vSX-AHM, was molecularly cloned and the nucleotide sequence of the spliced c-myc insert determined. No mutation was found within the c-myc coding sequence of this transforming clone when compared to the normal genomic progenitor. Thus, we concluded that no mutation within the human c-myc gene is required to induce primary avian embryo fibroblast transformation.

Animals↗
PubMed1986

Identification in chicken macrophages of a set of proteins related to, but distinct from, the chicken cellular c-ets-encoded protein p54c-ets.

Using an antiserum to a bacterially expressed polypeptide corresponding to 56 amino acids of v-ets, we previously identified in chicken tissues a protein of 54 kd (p54c-ets) which shares extensive sequence homology to the v-ets-encoded domain of the E26-transforming protein p135gag-myb-ets and is thus apparently encoded by the c-ets proto-oncogene. We report here that the anti-ets serum specifically identifies in chicken cells a second set of proteins of 60 kd (p60), 62 kd (p62) and 64 kd (p64) which appear to be highly related to each other but display only a limited domain of homology with p54c-ets and p135gag-myb-ets and are thus probably encoded by a gene(s) partially related to, but different from c-ets. In contrast to p54c-ets which is expressed at high levels in chicken lymphoid tissues, prominent syntheses of p62 and p64 were found in both normal and transformed chicken macrophages but not in avian cells corresponding to immature stages of the myeloid differentiation pathway. These observations together with the fact that differentiation of avian myeloblastosis virus-transformed myeloblasts into macrophage-like cells after treatment with 12-O-tetradecanoylphorbol-13-acetate is accompanied by the synthesis of p62 and p64 suggest a role for these proteins in chicken macrophage differentiation or function. Induction of differentiation of human leukemia cell lines HL60 and U937 into macrophages is also accompanied by the increased synthesis of c-ets-encoded 68 kd, 62 kd and 58 kd proteins.

Animals↗
PubMed1986

Comparison of constitutional and tumor-associated 11;22 translocations: nonidentical breakpoints on chromosomes 11 and 22.

Recurring, site-specific chromosomal rearrangements are associated with several human syndromes and malignant disorders. Such nonrandom translocations involving chromosome 22 in band q11 are numerous and found to be associated with a diversity of neoplasms as well as constitutional disorders. Chromosome 11 in bands q23-q24 is similarly involved in several types of tumors as well as in a recurring constitutional reciprocal translocation with chromosome 22. Here we report the use of chromosomal in situ hybridization to compare the translocation breakpoints in the cytologically indistinguishable constitutional t(11;22) and the tumor-related t(11;22) associated with Ewing sarcoma and peripheral neuroepithelioma. We have shown that the breakpoints can be distinguished from each other with respect to the locus encoding the constant region of the Ig lambda light chain (C lambda) at 22q11 and the ETS1 locus at 11q23----q24; ETS1 has been called hu-ets-1 or human c-ets-1. The tumor-associated chromosome 11 breakpoint is also different from those of leukemias with t(9;11) and t(4;11) translocations. Southern-blot analysis showed no rearrangement of ETS1 in these disorders in the region detected by our probe. ETS1 has also been mapped more precisely to 11q23.3----q24 by in situ hybridization to cells from an individual with an 11q23.3----qter deletion.

Cell Line↗
PubMed1986

Identification and preferential expression in thymic and bursal lymphocytes of a c-ets oncogene-encoded Mr 54,000 cytoplasmic protein.

The avian retrovirus E26 is unique among acute leukemia viruses in its ability to induce transformation of cells belonging to either the myeloid or erythroid lineage. The genome of E26 carries two oncogenes, v-myb and v-ets, that are derived from distinct cellular loci, c-myb and c-ets. We have constructed a plasmid vector that allows expression of part of the coding region of v-ets in a bacterial host. Antisera to the bacterially synthesized ets protein specifically precipitated the E26-encoded P135gag-myb-ets transforming protein. These antisera permitted us to identify a chicken c-ets-encoded protein of Mr 54,000 (P54c-ets) that shares 7 out of 10 of its major [35S]methionine-containing tryptic peptides with the v-ets-encoded domain of P135gag-myb-ets. Unlike P135gag-myb-ets and the Mr 75,000 translation product of c-myb (P75c-myb), which are nuclear proteins, P54c-ets was found to be predominantly cytoplasmic. P54c-ets is expressed at low levels in most cell lines and tissues tested, including bone marrow cells and circulating lymphocytes. P54c-ets, together with a minor but closely related Mr 56,000 protein, was found to be expressed at high levels in chicken thymocytes and bursal lymphocytes.

Animals↗
PubMed1986

Monoclonal antibodies to hemagglutinin-neuraminidase and fusion glycoproteins of Newcastle disease virus: relationship between glycosylation and reactivity.

Eighteen hybridoma lines obtained by immunization of mice with Newcastle disease virus (NDV) lentogenic strain La Sota or velogenic strain Italien produced hemagglutinating monoclonal antibodies. The 18 monoclones were divided into four groups according to their reactivity toward native hemagglutinin neuraminidase protein (HN), nonglycosylated HN precursor, and heat-denatured HN blotted on nitrocellulose membranes. Only group II reagents were reactive toward their targets in all conditions tested. They were considered sequence-specific antibodies. Group I antibodies did not require glycosylation but lacked reactivity towards the denatured glycosylated antigen. Monoclonal antibodies from group III recognized only the native HN. Group IV was made up of a single monoclone that lacked reactivity with NDV Italien but recognized the La Sota strain in hemagglutination inhibition and enzyme-linked immunosorbent assays. Five hybridoma lines produced monoclonal antibodies which neutralized viral infectivity but failed to inhibit hemagglutination. One monoclonal antibody obtained after immunization of mice with NDV La Sota showed a low neutralization index versus NDV Italien. Four monoclonal antibodies derived from mice immunized with NDV Italien showed higher neutralization indices towards this strain. Neither the denatured F protein nor its nonglycosylated precursor was reacted against by the five monoclonal antibodies.

Animals↗
PubMed1986

[Preparation and characterization of antisera specific to various polypeptide domains corresponding to the v-ets oncogene of the avian leukemia virus E26].

We prepared antisera to three distinct portions of the v-ets oncogene of the avian leukemia virus E26. An antiserum directed against the middle v-ets-encoded domain identifies in different chicken cell lines and normal tissues a c-ets-encoded protein of Mr 54,000 (P54c-ets) and three proteins of Mr 60,000 62,000 and 64,000 partially related to P54c-ets. Antisera directed against the aminoterminal v-ets-encoded domain failed to precipitate P54c-ets or P60/P64. Thus, the E26 specific v-ets oncogene displays a complex structure that includes several distinct portions, the genetic origin of which could be different.

Animals↗
PubMed1986

[Preparation and characterization of specific antisera directed against different polypeptide domains encoded by the c-myc oncogene for studying the expression of this gene introduced into quail or rat cells].

By using bacterial expression vectors, we have prepared antisera directed against two polypeptidic domains encoded by exons 2 and 3 of the human c-myc oncogene. These antisera which detect specifically the human c-myc proteins allow us to analyse the expression of human c-myc gene activated by retroviral sequences and introduced in quail embryo cells (QEC) or in established rat embryo fibroblastic cell line (208 F). Although human myc mRNA are expressed in the two cell types, the p64/p67 human c-myc proteins are only detected in the QEC.

Animals↗
PubMed1985

Bovine leukemia virus, a versatile agent with various pathogenic effects in various animal species.

The bovine leukemia virus is the etiological agent of a chronic lymphatic leukemia in cows, sheep, and goats. The same virus seems to induce a kind of wasting disease in experimentally infected rabbits. Antibodies to highly purified bovine leukemia viral Mr 51,000 glycoprotein and Mr 24,000 protein cross-react with human T-lymphotropic virus III/lymphadenopathy-associated virus antigens present in cultured lymphocytes of African patients suffering from acquired immune deficiency syndrome. Bovine leukemia virus has many structural and functional characteristics in common with the human T-lymphotropic viruses. The most striking feature of these retroviruses is the existence of a long open reading frame located at the 3' side of the provirus between the right end of the 3' side of env gene and the left end of the long terminal repeat. It is believed that the long open reading frame protein product acts in trans upon a number of genes to account for the biological effects of the virus.

Animals↗
PubMed1985

Bovine leukaemia virus and enzootic bovine leukosis.

Infection of bovines with bovine leukaemia virus (BLV) manifests itself in either of two ways: 30-70% of carriers develop persistent lymphocytosis (PL), with the viral genome integrated at a large number of different sites in the DNA of the affected B-lymphocytes, without causing any chromosomal abnormalities. Only 0,1-10% of carriers develop lymphoid tumours, which also consist of B-lymphocytes. In contrast to PL, however, they are of mono- or oligoclonal origin in terms of the integration site, which is characteristic for each tumour. All cells contain one or more copies of the viral genome, chromosomal aberrations are common and if deletions are present they are invariably found in the 5'-half of the virus DNA sequence. In both types of affected cells transcription is repressed in vivo, but transient virus production can be induced in vitro and detected by means of syncytia induction or haemagglutination. In vivo production of virus in some unknown cell is suggested by the presence of high antibody titres in infected animals, especially against the envelope glycoprotein gp51. This can be detected by various techniques such as immunodiffusion, radioimmune assay or ELISA. Monoclonal antibodies against gp51 have revealed 8 epitopes, 3 of which are recognized by neutralizing antibodies and one by a cytolytic antibody. The BLV genome, about 9 kb in size, have been cloned, and some of the information obtained on its molecular structure and function is discussed. It codes for at least 4 non-glycosylated and 2 glycoproteins. Of special interest is the recently discovered serological relationship between some of the non-glycosylated proteins and those of the human T-cell leukaemia virus. The functional role of BLV in leukaemogenesis is largely unknown. The presence of the viral genome seems to be necessary for the maintenance of the transformed state, but not its continuous expression nor an LTR-mediated promotion of transcription of cellular genes. No oncogene is carried by the virus. Although bovine leukosis is not of major economic importance, its eradication is desirable and feasible in countries with a relatively low incidence, by means of testing and elimination. For endemic situations vaccination would be preferable, and distinct possibilities exist for the development of gp51 based vaccines.

Animals↗
PubMed1984

Biologically active epitopes of bovine leukemia virus glycoprotein gp51: their dependence on protein glycosylation and genetic variability.

A panel of monoclonal antibodies to the bovine leukemia virus envelope glycoprotein (BLV gp51) has previously demonstrated the association of the biological activities of the virus (infectivity, syncytia induction) with three out of eight epitopes of gp51. In BLV-infected cells, the unglycosylated homolog of the precursor to the BLV envelope glycoproteins (gPr72env) is a 47,000-MW polypeptide. Immunoprecipitation studies with monoclonal antibodies show that the neutralizing antibody-inducing sites, although present in gPr72env, are not conserved in the 47,000-MW unglycosylated homolog. Finally, it is demonstrated that the neutralizing antibody-inducing sites of gp51 are subject to antigenic variation among BLV isolates of the same or different geographical origins.

Animals↗
PubMed1984

Bovine leukemia virus (BLV)--a structural model based on chemical crosslinking studies.

Nearest neighbor relationships between lipid and protein as well as between high-molecular-weight viral RNA and protein were investigated in bovine leukemia virus (BLV) particles using chemical crosslinking reagents. Separation of dimethyl suberimidate (DMS) induced lipid-protein complexes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the phosphoprotein pp 15 is linked to the lipid bilayer of the virus. By use of diepoxybutan (DEB) as crosslinking reagent p 12 and again pp 15 were found to be linked to the viral RNA. Based on these results and our previous data describing the spatial relationships of major structural proteins within BLV particles, a structural model of BLV is proposed.

Animals↗
PubMed1984

Bovine leukemia virus, a distinguished member of the human T-lymphotropic virus family.

Bovine leukemia virus (BLV) has many structural and functional characteristics in common with the human T-lymphotropic viruses (HTLVs). The most striking feature of these retroviruses is the existence of a long open reading frame (LOR) located at the 3' side of the provirus between the right end of the 3' side of env gene and the left end of the long terminal repeat (LTR). It is believed that the LOR protein product is of critical importance in the induction process of the tumor phase of bovine leukemia. Prevention of BLV infection will be attempted by vaccination. To that aim, careful study of BLV envelope glycoprotein epitopes has shown that epitopes F, G, and H play a major role in biological activities of the virus. Their native structure depends upon glycosylation of the peptide backbone.

Animals↗