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U R Rapp

Publications and source records attributed to U R Rapp.

At least 217 records · Page 12Linked to original sources
PubMed1983

New mammalian transforming retrovirus: demonstration of a polyprotein gene product.

A new acute transforming type C retrovirus was isolated from mice inoculated with a virus stock obtained by iododeoxyuridine induction of methylcholanthrene-transformed C3H/10T1/2 mouse cells. This virus, designated 3611-MSV, transforms embryo fibroblasts and epithelial cells in culture and induces fibrosarcomas in vivo. 3611-MSV is replication defective, requiring a type C helper virus for propagation both in vitro and in vivo. By using endpoint transmission of 3611-MSV to MMCE C17 mouse and FRE 3A rat cells, several nonproductively transformed clonal cell lines have been derived. Pseudotype virus stocks obtained from such clones transform cells in vitro, are highly oncogenic in vivo, and exhibit host range and serological properties that are characteristic of their helper virus component. Analysis of viral antigen expression in 3611-MSV-transformed cells has led to the demonstration of a 90,000-molecular-weight (Mr) polyprotein and a 75,000-Mr probable cleavage product, both containing the amino-terminal murine leukemia virus gag gene proteins p15 and p12. In contrast to gene products of many previously described mammalian transforming viruses, 3611-MSV-encoded polyproteins lack detectable protein kinase activity, and 3611-MSV-transformed cells resemble chemically transformed cell line C3H/MCA-5, from which 3611-MuLV was originally derived, in that they do not exhibit elevated levels of phosphotyrosine. By using molecular hybridization the 3611-MSV transforming gene was found to be distinct from previously described mammalian cellular oncogenic sequences, including c-ras, c-abl, c-fes, c-fms, c-sis, and c-mos.

Animals↗
PubMed1982

Transformation of MMC-E epithelial cells by acute 3611-MSV: inhibition of collagen synthesis and induction of novel polypeptides.

Mouse embryo epithelial cells MMC-E were transformed by novel fibrosarcoma-inducing murine sarcoma virus 3611-MSV. The cells were analyzed for the production and deposition of pericellular glycoproteins by immunofluorescence and by radioactive metabolic and cell surface labeling techniques followed by analysis in polyacrylamide gels and fluorography. The pericellular fibronectin matrix was lost, but unlike in virus-transformed fibroblastic cells, the production of fibronectin was not affected. The major differences detected were decrease in collagen production and initiation of synthesis of two major glycoproteins with Mr 58,000 and 60,000. Cell surface carbohydrate labeling indicated that after 3611-MSV transformation the cells expressed Mr 100,000 and 68,000 polypeptides. The present and previous results show that viral transformation of epithelial cells induces different transformed phenotypes that are associated with distinct alterations in pericellular glycoproteins.

Animals↗
PubMed1982

Dome formation by a retrovirus-induced lung adenocarcinoma cell line.

A cell line has been established from an alveologenic lung adenocarcinoma that develops in newborn NFS/N mice after i.p. inoculation with a carcinoma-inducing retrovirus. A clonal derivative of this cell line, 3041, forms adenocarcinomas when injected into syngeneic weanling mice and in culture retains several properties typical of alveologenic type 1 cells. These include morphological details, such as tight junctions and interdigitating microvilli in the areas of cell-cell contact, as well as the ability to transport fluid in culture. Fluid transport becomes evident in confluent cultures by the formation of domes or hemicysts. The formation of domes, which is considered to reflect a differentiated function of these secretory epithelial cells, can be enhanced more than 50-fold by treatment with dibutyryl cyclic adenosine 3':5'-monophosphate but only 5- and 3-fold by sodium n-butyrate and dimethyl sulfoxide, respectively. It is anticipated that the secretory alveologenic cell line 3041 described here will be useful for studies of both its pathological and its physiological properties.

Adenocarcinoma↗
PubMed1982

Murine leukemia virus-mediated transformation of a mouse epithelial cell line MMC-E.

Mouse embryo epithelial cells, MMC-E, were malignantly transformed in culture with MuLV derived from C3H/MCA 5 cells chemically induced by 5-iododeoxyuridine. The frequency of transformation was significantly enhanced if infection was followed by treatment with 100 ng of 12-O-tetradecanoylphorbol-13-acetate per ml. The virus-transformed cells retained their high plating efficiency in soft agar in the absence of 12-O-tetradecanoylphorbol-13-acetate and formed neoplasms in nude mice.

Animals↗
PubMed1980

Genetic transmission of retroviral genes and cellular oncogenes.

Several different families of retrovirus genome have been found to exist, each in multiple copies, in the cellular DNA of rodents and primates. There are at least four distinct families of genome in rodents: two type C families, the MTV family and another related to mouse type A particles. In primates there are also at least two families of endogenous type C virogenes and a third type D virogene family. Both in rodents and in primates, the virus-related sequences constitute almost 0.1% of the cellular genome. We have been able to generate transforming viruses, starting with endogenous mouse 'helper' type C viruses by passing them through chemically transformed mouse cells and selecting for variant viruses that have acquired the ability to induce normal cells to display anchorage-independent growth. These viruses produce both sarcomas and carcinomas in the animal; clones that produce only pulmonary carcinomas have also been selected. These presumably have arisen by recombination between the helper and 'transforming' sequences derived from the cells. Moloney sarcoma virus-transformed cells produce a new peptide, called sarcoma growth factor (SGF), that makes normal cells take on some of the properties of transformed cells. Studies with temperature-sensitive viral mutants show that the production of SGF is under the control of the transforming genes of the sarcoma virus.

Animals↗
PubMed1980

Murine sarcoma growth factors affect the growth and morphology of cultured mouse epithelial cells.

A mouse embryo epithelial cell line, MMC-E, was used to study the effects of purified murine sarcoma growth factors (SGFs) on the growth of epithelial cells. Murine SGF was a partially purified preparation from the serum-free culture media of mouse fibroblasts transformed by Moloney murine sarcoma virus. SGFs stimulated DNA-synthesis in resting cells and induced them to grow to higher densities than control cells. With continued exposure to SGFs, MMC-E cells lost their postconfluency inhibition of division and formed small expanding foci. When the SGFs were removed and the cells were subcultured, they regained their normal phenotype, showing that the effects of SGFs are reversible on these epithelial cells. SGFs could also stimulate the MMC-E epithelial cells to grow in soft agar, like the syngeneic fibroblasts (MMC-F) from the same mouse embryo, but slower than the control fibroblastic clone. Microgram quantities of SGFs were needed to stimulate soft agar growth of MMC-E cells. The results indicate that SGF can bring about a phenotypic change in the growth pattern of epithelial cells as well as fibroblastic cells.

Animals↗
PubMed1980

Cell surface receptors for endogenous mouse type C viral glycoproteins and epidermal growth factor: tissue distribution in vivo and possible participation in specific cell-cell interaction.

We have described previously the detection and tissue distribution of free cell surface receptors for ecotropic R-MuLV envelope glycoprotein and the growth factor EGF in vivo [1]. More recently, we have reported the chromosomal map position of the ecotropic viral receptor and its conservation between subspecies of the genus Mus [2]. This work has shown, for the first time, the presence of multiple, independently segregating cell surface receptor genes specific for different classes of ecotropic type C viral envelope glycoprotein. In this report we extend these findings and identify chromosome 2 as coding for the receptor used by M813, an ecotropic MuLV from a feral Asian mouse. This new receptor is probably also used by oncogenic, recombinant (MCF class) MuLV of C3H origin.

Animals↗
PubMed1980

Generation of oncogenic mouse type C viruses: in vitro selection of carcinoma-inducing variants.

Type C retroviruses are endogenous in most vertebrate species. These viruses generally are of low pathogenicity in their natural hosts. Variants that contain cell-derived transforming genes have been isolated infrequently in the past upon continued passage in vivo. We report here a procedure that allows the isolation of new mouse leukemia-, sarcoma-, and carcinoma-inducing type C viruses entirely in cell culture. The viruses generated after passage in chemically transformed mouse cells and selectron in epithelial mink lung cells produced pulmonary adenomas and adenocarcinomas and also ovarian carcinomas. Viruses with cell-transforming capacity, as determined by their ability to induce normal murine or mink cells to form progressively growing colonies in soft agar, appeared only transiently (2-4 days) after acute infection of "spontaneously" or chemically transformed mouse cells by nontransforming helper viruses. These transiently appearing transforming viruses can be "captured" by selecting the cells that respond to their newly acquired growth-stimulating ability. This system may lend itself to the systematic isolation of tissue-specific transforming functions from any cell that can be efficiently infected by retroviruses.

Adenoma↗
PubMed1979

Genes controlling receptors for ecotropic and xenotropic type C virus in Mus cervicolor and Mus musculus.

Gene loci controlling cell surface receptors for murine leukemia virus were studied by using murine X Chinese hamster hybrid cells. Hybrids which exclusively segregate murine chromosomes were made by fusing Mus cervicolor and Mus musculus lymphocytes to hamster fibroblasts. Sensitivity to Moloney murine leukemia virus infecotion and specific binding of the envelope glycoprotein of Rauscher murine leukemia virus (gp70) cosegregate and isozyme analysis show an association with chromosome 5 in both species. With the possible exception of one clone, no evidence was found for a proviral integration site independent of chromosome 5. Evidence is presented for additional unlinked ectropic and xenotropic receptors independent of chromosome 5.

Animals↗
PubMed1978

Generation of new mouse sarcoma viruses in cell culture.

Endogenous nontumor-producing type C viruses from C3H mice were used to generate rapid, solid tumor-inducing variants in cell culture. The new mouse sarcoma viruses induce undifferentiated sarcomas with a short latency period upon inoculation into newborn NIH Swiss mice. Transforming viruses appear only transiently, at a time when the virus-infected cells show morphologic alterations; both before and after this time, transforming viruses cannot be detected. These results show that variants of endogenous type C virus which contain transforming genes (oncogenes) can arise during spread of the endogenous virus in fibroblast lines in vitro as well as in susceptible tissues in vivo.

Animals↗
PubMed1978

Cell surface receptors for ecotropic MuLV: detection and tissue distributions of free receptors in vivo.

The expression of available cell surface receptors for binding of the major envelope glycoprotein of Rauscher MuLV, gp71, was studied in freshly prepared tissues of the low-leukemic mouse strain CBA. The presence of such receptors is a requirement for infection and therefore also for transformation of cells in vitro by ecotropic MuLV. This paper describes the conditions of the binding assay for radiolabelled RLV gp71 and freshly prepared lymphoid cells under which binding occurs as a function of time and cell number. With this assay, available receptors for RLV gp71 were detected in all lymphoid as well as some non-lymphoid tissues, most notably brain. The lack of binding in other non-lymphoid tissues was not due to the presence of gp71 specified by endogenous ecotropic MuLV, as was determined by a sensitive group specific RIA. These results demonstrate that the distribution of receptor sites necessary for infection by ecotropic MuLV does not directly correlate with the tissue distribution of malignant transformation that is most commonly induced by these endogenous viruses. Therefore, susceptibility to infection by ecotropic MuLV, as determined by the expression of viral receptors, is not sufficient to determine the target organ for MuLV-induced oncogenesis.

Animals↗
PubMed1978

Generation of oncogenic type C viruses: rapidly leukemogenic viruses derived from C3H mouse cells in vivo and in vitro.

A type C virus was isolated from C3H/10T1/2 mouse cells in culture after activation with iododeoxyuridine. This virus was poorly infectious for mouse cells and did not cause tumors upon inoculation into newborn NIH Swiss mice. Variants with increased infectivity for mouse cells were then derived both in vivo and in vitro by selecting for variants able to grow to high titers. The highly infectious variants were found to induce mouse fibroblasts to grow in soft agar. When the viruses were inoculated into newborn NIH Swiss mice, 100% of the animals died of leukemia within 4 months. Solid tumors developed at the injection site. Both mouse-tropic and dualtropic viruses were isolated from the leukemic mice and plaque purified. The first group of viruses produced large syncytial plaques on rat XC cells and did not grow in mink cells. The viruses of the other group replicated well in both mouse and mink cells, producing morphologic changes similar to transformation but not XC syncytia; they, therefore, are members of the newly described MCF class of mouse type C viruses. Isolates from either group were highly leukemogenic on retesting, the mean latent period being 67 days for a mouse-tropic virus and 105 days for one of the dual-tropic viruses. The results led to the conclusion that the better a mouse type C virus grows in cell culture the more effective it is as a leukemogen. Further, it is possible to start with a weakly infectious, nonleukemogenic virus and to convert it to a rapidly replicating, highly leukemogenic virus by passage either in cell culture or in the animal. The availability of a defined series of viruses from a low-leukemia mouse strain that differ greatly in their biologic properties should facilitate studies of the molecular basis for the acquisition of type C virus oncogenicity.

Animals↗
PubMed1978

Rescue of endogenous 30S retroviral sequences from mouse cells by baboon type C virus.

Mus musculus SC-1 cells were infected with M7 baboon type C virus. The progeny of this infection included viral pseudotypes that contained M7 helper virus and endogenous 30S retrovirus-associated sequences derived from SC-1 cells (RAS). The RAS sequences are unrelated by nucleic acid hybridization criteria to previously described types of murine retroviruses and do not code for known murine viral structural proteins. The RAS genome is present in multiple copies in the DNA of laboratory (M. musculus) and Asian (M. caroli and M. cervicolor) mice, is expressed in the RNA of uninfected mouse cells, and can be efficiently rescued by type C, but not type B, viruses. RAS is closely related to 30S virus-associated RNA in NIH/3T3 and BALB/c JLSV-9 cells and may be analogous to the defective 30S RNA sequences found in rats.

Animals↗