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Biomedical subjects

J Feunteun

Publications and source records attributed to J Feunteun.

At least 91 records · Page 5Linked to original sources
PubMed1986

The hamster papovavirus: evolutionary relationships with other polyomaviruses.

The hamster papovavirus (HaPV) is a polyoma virus with a restricted tumor spectrum. It is actively replicated in hair follicle tumors arising spontaneously in young Syrian hamsters. It can also induce lymphomas and leukemias in newborn hamsters. The complete nucleotide sequence of a cloned HaPV has been established recently. This report presents a comparison of this sequence with other polyomavirus genomes (polyoma, SV40, BKV, LPV) by matrix dot analysis and electron microscopy heteroduplex mapping. The results demonstrate a close relationship between the HaPV and the murine polyoma virus and designate the LPV as the closest relative among the primate polyomaviruses.

Animals↗
PubMed1986

Influence of amino acids encoded in the 3' open reading frame of the SV40 early region on transformation and antigenicity of large T antigen.

The mutant dlA2414 bears a frame-shift deletion of nucleotides 2936-2927 in the coding sequence for the simian virus 40 (SV40) large T antigen. Based on its nucleotide sequence, this mutant should produce a T antigen containing the first 627 authentic large T antigen amino acids followed by 97 amino acids encoded in the alternate open reading frame at the 3' end of the early region. This protein resembles the hypothetical T* protein that would be translated from an early SV40 mRNA if it were spliced to permit utilization of the open reading frame. We show that stable mouse cell lines can be generated that express the T antigen produced by dlA2414 and that this T antigen has an altered carboxy terminus. In addition, the expected tryptic peptides were missing from the large T antigen and replaced by more hydrophobic peptides. The T*-like protein produced by dlA2414 was apparently less stable than wild-type T antigen and did not stably complex with the cellular phosphoprotein p53. This protein retained the ability to immunize mice against a challenge of syngeneic SV40-tumor cells. The dlA2414 T antigen was expressed at the surface of cells as shown by in vitro lymphocyte-mediated cytotoxicity assay. The results presented here also showed that the expression of a T*-like protein at the cell surface is not likely to be essential for tumorigenesis of cells transformed by SV40.

Amino Acids↗
PubMed1985

A new member of the polyomavirus family: the hamster papovavirus. Complete nucleotide sequence and transformation properties.

The hamster papovavirus (HapV) is associated with multiple skin epitheliomas of the Syrian hamster. We have sequenced its genome. It is a double-stranded circular DNA of 5366 bp. The hypothetical genomic organization deduced from this nucleotide sequence is clearly of the polyoma type with the two strands coding in the opposite directions from a noncoding region that shows some of the features of a replication origin and a transcription control region. The amino acid sequences predicted from the open reading frames show an average of 50% homology with polyoma-coded polypeptides. The HapV is, after polyoma, the second example of a papovavirus coding for a middle T antigen. The cloned DNA can immortalize primary rat embryo cells and transform an established rat cell line. The viral DNA is stably integrated into the host genome.

Animals↗
PubMed1985

Isolation of renin-producing human cells by transfection with three simian virus 40 mutants.

A human juxtaglomerular cell (JGC) tumor was used for the immortalization of renin-secreting cells. The transfection of primary JGC with three different simian virus 40 (SV40) mutants resulted in the continuous production of renin-secreting cells. The most efficient renin-producing cells (producing about 400 pg of renin per 24 hr per ml of culture medium) were those transfected with the PAS SV40 mutant. The renin production was stable and the cell cultures have been maintained for greater than 1 year. Two types of cells were cultured together and could not be separated: round and birefringent cells, which exhibited features of mast cells, and elongated cells containing myofilaments and secretory granules. Immunocytochemical staining showed the presence of renin in this latter cell type. The renin produced by the transfected cells was not stored within the cells but was released rapidly into the medium. More than 95% of the renin produced was prorenin, which, after activation, had characteristics similar to those of pure human standard renin as to its enzymatic, immunologic, and biochemical properties, except that it was less glycosylated. These stable JGC tumoral cell lines provide a unique system for studying human renin biosynthesis and its regulation in vitro.

Antigens, Viral, Tumor↗
PubMed1985

Restriction endonuclease cleavage map of the DNA of hamster papovavirus.

A detailed restriction map of hamster papovavirus (HaPV)-DNA has been constructed on the basis of the complete nucleotide sequence of the viral genome. The HaPV DNA restriction map is totally divergent from those of all other recently known papovaviruses. This map will be useful for future functional studies of the HaPV genome.

Animals↗
PubMed1984

Reversibility of the transformed and neoplastic phenotype. IV. Effects of long-term interferon treatment of C3H/10T1/2 cells transformed by methylcholanthrene and SV40 virus.

The effects of long-term treatment with mouse interferon on the phenotype of untransformed C3H/10T1/2 cells and cloned derivatives transformed by methylcholanthrene (MCA) and Simian virus 40 (SV40) were investigated. Continuous presence of interferon induced morphologic reversion, with the development of thick, submembranous filaments in MCA-transformed cells, whereas no morphological effects were detected in SV40-transformed cells. Interferon inhibited the proliferation of all three cell lines and maintained low saturation densities. However, prolonged treatment of MCA-transformed cells with interferon rendered them tolerant toward the anti-proliferative and antiviral activities of interferon although 2-A synthetase activity was induced. Interferon treatment reduced the capacity of both MCA and SV40-transformed cells to form colonies in agar and decreased the tumorigenicity of MCA-transformed but not SV40-transformed cells in mice. These results indicate that the same cell type transformed by different means has different sensitivities to a number of interferon-induced changes in the cell phenotype.

Animals↗
PubMed1984

Sequence homology between polyoma virus, simian virus 40, and a papilloma-producing virus from a Syrian hamster: evidences for highly conserved sequences.

Sequence homology between the genomes of a hamster papovavirus (HaPV), polyoma virus (Py), and Simian virus 40 (SV40) has been studied by filter hybridization and electron microscopy under conditions of varying stringency. Hybrids between the HaPV and SV40 DNAs could be demonstrated only under nonstringent conditions. The region of highest homology was mapped in the early region of the SV40 genome. Extensive homology was detected between the genomes of HaPV and Py under stringent hybridization conditions, indicating at least 80% base matching in the regions of strongest sequence homology. These sequences were localized within both the early region and the late region of the Py genome. The homologous DNA segments mapped in the Py and the SV40 genomes are among the most strongly conserved regions in the polyoma (miopapova)-virus group.

Animals↗
PubMed1983

Immortalization of rodent embryo fibroblasts by SV40 is maintained by the A gene.

SV40 can induce proliferation of primary cells from various origins and by making them escape from senescence confer a potential of unlimited division characteristic of established cell lines. We have studied this effect called immortalization with various mutants of the SV40 early genes. The results establish that the immortalized phenotype is controlled by the A gene in a reversible fashion. Cells immortalized at 33 degrees by a tsA mutant, revert to a "mortal" or senescent-like phenotype after temperature shift up to 39 degrees. The nature of these striking phenotypic changes is discussed.

Animals↗
PubMed1983

Evolutionary relationships between papovaviruses and their hosts.

The papovaviridae family consists of two genera, the papillomaviruses (PV) and the polyomaviruses (Py-V). Both genera are distinguished by morphological (larger sizes of the PV) and several biological characteristics. The genomes of either of the two genera share highly conserved DNA regions and a common antigenic determinant, located in their major capsid polypeptides. On the basis of these data an evolutionary relationship among the members of PV and Py-V, respectively, has been suggested. No homology has been found for either DNA- or protein sequences between PV and Py-V and the question of a common ancestor for both viral genera remains open. We have started to characterize the genome of a papilloma producing papovavirus of the Syrian hamster (HaPV). Most of the known biological characteristics of the HaPV suggest it should be classified as a papilloma-like virus. However, the molecular weight of about 3.5 X 10(6) daltons found for the circular duplex DNA lies within the range given for SV 40 and polyoma virus (Py). Analysis of the HaPV genome by cleavage with 21 different restriction endonucleases, location of specific binding sites of phage T 4 gene 32 protein and E. coli RNA polymerase on the viral DNA demonstrated that the HaPV differed distinctly from all other currently known papovaviruses. The HaPV genome was also analyzed by filter hybridization and electron microscopy under conditions of varied stringency for nucleotide sequence homology with the genomes of different papovaviruses of both genera. Whereas no homologous DNA regions could be found between the genomes of HaPV and the human PV types 1 and 4, only under nonstringent conditions (Tm-43 degrees C) stable hybrids were formed between HaPV-, SV 40- and the DNA of a PV isolated from Mastomys natalensis (MnPV). On the other hand extensive homology was detected between the genomes of HaPV and Py even under stringent hybridization conditions (Tm-28 degrees C). The homologous DNA segments mapped on the Py and partially on the SV 40 genome were found to be the most strongly conserved DNA regions among the Py-V genus. These results are discussed with respect to a classification of the HaPV within the papovaviridae family.

Animals↗
PubMed1983

The genetics of transformation by SV 40.

Experiments using the tsA 58 allele of the SV 40-A gene have demonstrated that the SV 40 large T-antigen is strictly required both for immortalization and induction anchorage independence of cells. It has been suggested that the immortalized phenotype is mediated by an extra cellular factor. The synthesis and/or the excretion of this factor in a medium is controlled by the A gene.

Alleles↗
PubMed1982

Prereplicative events involving simian virus 40 DNA in permissive cells.

Simian virus 40 DNA molecules were found to be unable to replicate for 9 h after infection, even in cells that were already replicating the DNA of preinfecting simian virus 40; after 9 h, the ability of the DNA to replicate began to rise sharply. The kinetics of activation indicated that each DNA molecule undergoes a series of slow consecutive reactions, not involving T-antigen, before it can replicate. These pre-replicative molecular transformations probably involve configurational changes; their nature and their relation to the initiation of viral DNA synthesis is discussed. Observation of the replicative behavior of one viral DNA in the presence of another was made possible by the use of two different mutants with distinguishable DNAs: a viable deletion mutant containing DNA insensitive to TAqI restriction enzyme was used to provide viral functions required for replication, and a tsA mutant with TaqI-sensitive DNA was introduced at various times as a probe to determine the ability of the DNA to replicate under different conditions.

DNA Replication↗
PubMed1982

Phosphorylation pattern of large T antigens in mouse cells infected by simian virus 40 wild type or deletion mutants.

The phosphorylation sites of simian virus 40 (SV40) large tumor (T) antigens have been extensively studied in productive infection of monkey cells. In this study, we analyzed the phosphorylation sites of large T antigen from SV40-infected nonpermissive mouse cells by partial proteolysis fingerprints and analysis of the phosphoamino acids present in the resulting fragments. The wild-type virus and deletion mutants (dl1263, dl1265, dl2194, and dl2198) were used for infection. On the basis of our results and published data (M. Schwyzer, R. Weil, and H. Zuber, J. Biol. Chem. 225:5627-5634, 1980), a cleavage map of large T antigen was established. It was reported that at least four sites of phosphorylation were present. The amino-terminal part of the molecule contained both phosphoserine and phosphothreonine. One phosphothreonine residue was located in the prolinerich C-terminal end of the molecule at position 701 or 708. On the basis of the concensus as to the amino acid sequence surrounding the recognition sites for protein kinases, it was possible to more precisely locate this phosphothreonine at residue 701. Moreover, the C-terminal part of the molecule contained phosphoserine at a more internal position. In addition, this study firmly established the presence of a phosphothreonine in the N-terminal part of large T antigen. In conclusion, it was shown that the location of phosphorylation sites of large T antigen produced by nonpermissive mouse cells infected by SV40 is strikingly similar to that reported by other groups for large T antigen produced by SV40-infected permissive cells.

Animals↗
PubMed1981

Mutant carrying deletions in the two simian virus 40 early genes.

We isolated a simian virus 40 mutant, dl2194, which carried deletions in both early genes. One deletion removed 234 base pairs in the 54/59 region within the small-t-antigen coding sequence and the large-T-antigen gene intron. The second deletion removed 57 base pairs at the C terminus of the large-T-antigen coding sequence (0.20 map unit). dl2194 was a viable mutant, it carried a normal helper function for adenovirus growth on monkey cells, and it displayed the transformation properties of a small-t-antigen-negative single mutant. Therefore, none of the known large-T-antigen functions seemed to be altered by the C-terminal deletion.

Adenoviruses, Human↗
PubMed1979

A ribonuclease-resistant region of 5S RNA and its relation to the RNA binding sites of proteins L18 and L25.

An RNA fragment, constituting three subfragments of nucleotide sequences 1-11, 69-87 and 89-120, is the most ribonuclease-resistant part of the native 5S RNA of Escherichia coli, at 0 degrees C. A smaller fragment of nucleotide sequence 69-87 and 90-110 is ribonuclease-resistant at 25 degrees. Degradation of the L25-5S RNA complex with ribonuclease A or T2 yielded RNA fragments similar to those of the free 5S RNA at 0 degrees C and 25 degrees C; moreover L25 remained strongly bound to both RNA fragments and also produced some opening of the RNA structure in at least two positions. Protein L18 initially protected most of the 5S RNA against ribonuclease digestion, at 0 degrees C, but was then gradually released prior to the formation of the larger RNA fragment. It cannot be concluded, therefore, as it was earlier (Gray et al., 1973), that this RNA fragment contains the primary binding site of L18.

Base Sequence↗
PubMed1979

Nucleotide sequence deletions within the coding region for small-t antigen of simian virus 40.

Simian virus 40 early mutants with deletions mapping in the 0.53-0.60 region have been sequenced by the Maxam and Gilbert approach. All these deletions effect the small-t gene. The size of the shortened small-t-related polypeptides produced by several of the mutants has been compared with the molecular weight as deduced from the nucleotide sequence. There was good agreement for the mutants dl890, dl891, and dl2102. For dl2121 and dl2122 the small-t-related protein was considerably larger than expected. It is possible to explain this result on the basis of the nucleotide sequence: the normal splicing event of the small-t mRNA still occurs, but as the deletion shifts the reading frame, translation of the small-t-related polypeptide continues beyond the small-t splice, but in a different reading frame than large-T. Mutants dl883, dl884, and dl2112 have lost one of the small-t splicing boundaries, and no (or minute amonts of) small-t-related protein has been observed in mutant-infected cells. The possible relationship between splicing and transport of polyadenylic acid-containing mRNA from the nucleus to the cytoplasm in vertebrae cells is discussed.

Antigens, Viral↗