PubMed Health⌕ Search

Biomedical subjects

H R Bose

Publications and source records attributed to H R Bose.

At least 55 records · Page 3Linked to original sources
PubMed1988

Transformation of avian lymphoid cells by reticuloendotheliosis virus.

Avian reticuloendotheliosis virus (REV-T) is the most virulent of all retroviruses, inducing an invariably fatal leukemia in chickens with a latent period of 7-10 days. Unlike avian cells transformed by other acutely transforming viruses, lymphoid cells transformed by REV-T are immortalized. Furthermore, in vitro derived, REV-T transformed cells which do not produce virus are tumorigenic and induce lethal reticuloendotheliosis when injected into histocompatible birds. Thus REV-T transforms its target cell both in vitro and in vivo. In addition this transformation is independent of any helper virus functions. Like other acute leukemia viruses, REV-T is replication-defective and must co-replicate with a reticuloendotheliosis associated virus (REV-A). During evolution, a substantial portion of its genome has been deleted and replaced with a host-derived genetic sequence, designated v-rel. Presumably, the v-rel oncogene was transduced from a normal turkey DNA locus, c-rel. There are 9 regions of homology between c-rel and v-rel, however, several differences exist between these genes, suggesting that transformation by REV-T results from the production of an altered v-rel protein. The v-rel sequence is distinct from other known oncogenes and encodes a 57-kDa phosphoprotein. In REV-T transformed cells, this pp57v-rel protein is localized in the cytoplasm. The product of the v-rel oncogene is present at a low level, representing only about 0.003% of total methionine-labelled protein. In addition, pp57v-rel is relatively stable, having an estimated half-life of 4-10 h. The v-rel protein when purified close to homogeneity is complexed with a 40-kDa cellular phosphoprotein in transformed lymphoid cells and possesses serine kinase activity. This review discusses the molecular aspects of transformation by REV-T in the context of other oncogene-encoded proteins.

Animals↗
PubMed1988

The v-rel oncogene product is complexed to a 40-kDa phosphoprotein in transformed lymphoid cells.

The transforming protein encoded by the v-rel oncogene of avian reticuloendotheliosis virus (REV-T) is a very low copy number molecule in the cytosol of transformed cells. Analysis of cytosolic extracts from a REV-T-transformed lymphoid cell line by gel filtration on Sephacryl S-300 indicated that most of the v-rel oncogene product, pp59v-rel, eluted with an apparent molecular mass of 400 kDa. The size of this complex was confirmed by analysis on a fast-protein liquid chromatography gel filtration column. A 40-kDa cellular protein copurified with pp59v-rel on sequential gel filtration on Sephacryl S-200 and immunoaffinity chromatography with a monoclonal antibody directed against pp59v-rel. The 40-kDa cellular protein could also be immunoprecipitated together with pp59v-rel from cell extracts of [35S]methionine-labeled cells, suggesting that pp59v-rel is complexed with the 40-kDa protein in transformed lymphoid cells. Both the 59- and 40-kDa proteins were phosphorylated when the highly purified preparation containing pp59v-rel was incubated with [gamma-32P]ATP and 10 mM MgCl2 in vitro. The identity of the kinase in the highly purified preparation containing pp59v-rel, however, is unknown. Immune complexes recovered from extracts of REV-T-transformed lymphoid cells labeled with [32P]orthophosphate also contained the 59- and 40-kDa phosphoproteins. These observations suggest that pp59v-rel is complexed with a 40-kDa cellular phosphoprotein to form a 400-kDa heteropolymer in the cytoplasm of transformed lymphoid cells.

Animals↗
PubMed1987

The transforming protein of avian reticuloendotheliosis virus is a soluble cytoplasmic protein which is associated with a protein kinase activity.

We have identified the product (p57v-rel) of the transforming gene, v-rel, of avian reticuloendotheliosis virus (REV-T) using antisera generated against nonoverlapping sequences representing the middle and carboxy-terminal regions of the v-rel protein expressed in Escherichia coli (N.K. Herzog and H.R. Bose, Jr., 1986, Proc. Natl. Acad. Sci. USA 83, 812-816). The amino-terminal region of the v-rel protein was also expressed in E. coli and used to generate antisera. The immunoglobulin-enriched fractions of these antisera were used to determine the subcellular location of p57v-rel in REV-T transformed lymphoid cells. Cells were fractionated into nuclear, mitochondrial, microsomal, and cytoplasmic fractions. The majority of p57v-rel was found in the cytoplasm. Examination of REV-T transformed lymphoid cells labeled with 32Pi revealed that the majority of the phosphorylated form of the v-rel protein was also found in the cytoplasm. Indirect immunofluorescence of REV-T transformed cells gave a diffuse cytoplasmic pattern indicating that p57v-rel was not associated with any discrete cellular organelle. The distribution of p57v-rel was similar in REV-T transformed lymphoid cells labeled with [35S]methionine for short and long periods of time, suggesting that p57v-rel is a soluble cytoplasmic protein throughout its lifetime. The v-rel protein was phosphorylated when immune complexes precipitated from transformed cells with the immunoglobulin fractions obtained from antisera against the amino-terminal, middle, and carboxy-terminal regions of v-rel were incubated with [gamma-32P]ATP and Mn2+. The phosphorylation of p57v-rel in the in vitro immune complex kinase assay was inhibited when the immunoglobulin-enriched fraction of these antisera was preincubated with the homologous v-rel fusion proteins. Preincubation with heterologous proteins did not block the phosphorylation of p57v-rel. These observations suggest that p57v-rel is associated with a protein kinase activity. Most of the kinase activity was found in the soluble cytoplasmic fraction of transformed cells. The transforming protein encoded by v-rel is a relatively stable protein with a half-life of approximately 7 to 8 hr in transformed lymphoid cells.

Cell Transformation, Viral↗
PubMed1986

Expression of the oncogene of avian reticuloendotheliosis virus in Escherichia coli and identification of the transforming protein in reticuloendotheliosis virus T-transformed cells.

The genome of reticuloendotheliosis virus T (REV-T) includes a unique oncogene v-rel, which is transcribed in low amounts into a 3.0-kilobase subgenomic mRNA in REV-T-transformed lymphoid cells. To identify the v-rel protein, REV-T DNA sequences were cloned into bacterial plasmid vectors designed to achieve expression of foreign DNA sequences in Escherichia coli. Portions of the v-rel gene were joined to the 5' segment of the trpE gene. Upon induction of trpE with indoleacrylic acid, large amounts of trpE-v-rel fusion proteins were produced by the bacteria carrying these recombinant plasmids. Two trpE-v-rel fusion proteins were synthesized in E. coli, which collectively represent three-quarters of the predicted v-rel protein. Polyclonal antisera were generated to trpE-v-red fusion proteins. These antisera were used in immunoblotting experiments to identify a 57-kDa v-rel protein in REV-T-transformed lymphoid cells lines and REV-T-infected chicken embryo fibroblast cultures. The v-rel gene expressed in E. coli under lac control was found to produce a 56-kDa protein. Although REV-T-transformed and Marek disease virus-transformed lymphoid cells contain c-rel mRNA transcripts, a c-rel protein could not be detected with antisera directed against v-rel fusion proteins.

Animals↗
PubMed1986

Oncogene expression in reticuloendotheliosis virus-transformed lymphoid cell lines and avian tissues.

The genome of reticuloendotheliosis virus (REV-T) contains a unique oncogene, designated v-rel, which is inserted into the env region. Employing a cloned rel DNA probe, a single 2.9- to 3.0-kilobase v-rel mRNA was identified in poly(A)+ RNA from REV-T-transformed lymphoid cell lines. A 4.0-kilobase rel-specific transcript corresponding to the cellular homolog of the v-rel oncogene was identified in MSB-1 cells, a herpesvirus-transformed lymphoid cell line. Cytodot hybridization was used to quantitate the levels of rel, c-rel, c-myc, c-myb, c-abl, c-fms, c-Ha-ras, c-Ki-ras, c-src, c-yes, c-mos, and c-sis mRNA in REV-T-transformed cells. The levels of rel transcription in REV-T-transformed cells were elevated only two to eightfold over levels found in the transformed immature avian lymphoid cell line MSB-1. The relatively modest levels of rel transcription in REV-T-transformed cells and the significant differences between the lengths of the v-rel and c-rel mRNA suggest that REV-T transformation is the result of the production of an altered rel protein. The c-rel proto-oncogene is expressed in all avian hematopoietic tissues but is not expressed at significant levels in brain and muscle. The transcription of other proto-oncogenes is not enhanced in REV-T-transformed lymphoid cell lines.

Animals↗
PubMed1985

Effect of tunicamycin on the development of the cytopathic effect in Sindbis virus-infected avian fibroblasts.

In Sindbis virus-infected avian cells the development of the cytopathic effect is correlated with the disruption of plasma membrane function. Sindbis virus inhibits the activity of the Na+K+ATPase, a membrane-associated enzyme complex which regulates intracellular monovalent cation levels. Tunicamycin, which blocks envelope protein glycosylation, prevents inhibition of Na+K+ATPase activity and the development of morphological changes in Sindbis virus-infected cells. Although inhibition of Na+K+ATPase activity is not essential for the termination of host protein synthesis, membrane-mediated events may favor the selective translation of viral proteins. The termination of host protein synthesis does not contribute to the development of these cytopathic changes in the time frame examined. In tunicamycin-treated, Sindbis virus-infected cells, unglycosylated E1 is inserted into the plasma membrane but virus release is prevented. In productively infected cells, therefore, the inhibition of Na+K+ATPase activity and the development of the cytopathic effect may result from terminal events in virus assembly and/or virus release.

Animals↗
PubMed1985

Inhibition of hepatic phosphoenolpyruvate carboxykinase by avian reticuloendotheliosis viruses.

Severe weight loss is associated with many malignant diseases of humans and animals. Avian reticuloendotheliosis viruses (RE viruses) induce runting in experimentally infected chickens. Chickens infected with a replication-competent RE virus, reticuloendotheliosis-associated virus, weighed 30-50% less than control birds at the time of death. Chickens infected with reticuloendotheliosis virus, a replication-defective acute leukemia virus, weighed 30% less than the controls. The runting induced by RE viruses does not occur because of reduced food intake. Activities of phosphoenolpyruvate carboxykinase, a key gluconeogenic enzyme in the liver, were reduced approximately 40 and 50%, respectively, by infection with reticuloendotheliosis-associated virus and reticuloendotheliosis virus. RE virus infection, however, did not affect the hepatic pyruvate carboxylase activity, indicating that inhibition of phosphoenolpyruvate carboxykinase is not due to a general inhibition of all liver enzymes. Birds given injections of UV-inactivated RE viruses or reticuloendotheliosis virus-transformed, non-virus-producing tumor cells also exhibited a reduction in phosphoenolpyruvate carboxykinase activity.

Animals↗
PubMed1984

Alterations in monovalent cation transport in Sindbis virus-infected chick cells.

Influx experiments using the potassium tracer 86Rb+ indicated that the activity of the Na+K+ ATPase, or sodium pump, was reduced 40-50% as a consequence of Sindbis virus infection of avian fibroblasts. The inhibition of this ouabain-sensitive, active transport system temporally correlated with a decrease in the intracellular K+ concentration and the termination of cellular protein synthesis. By contrast, the rate of influx facilitated by the furosemide-sensitive (Na+K+Cl-) cotransport system was only slightly depressed. Efflux experiments indicated that no alterations in the relative rate of nonspecific permeability or "leakage" of K+ could be detected in chick cells infected by Sindbis virus. The amount of [3H]ouabain bound to Sindbis virus-infected cells paralleled the reduction in Na+K+ ATPase activity. These binding studies revealed no difference in the number of Na+ pump sites. The Km of ouabain binding, however, increased approximately 3.5-fold in the virus-infected cells. No change in the apparent affinity of the Na+ pump for K+ could be detected, yet the Vmax for ouabain-sensitive K+ transport was decreased. These experiments suggest that a reduction in Na+K+ ATPase turnover results in the altered intracellular monovalent cation levels found in Sindbis virus-infected chick cells.

Animals↗
PubMed1984

Reticuloendotheliosis virus and disturbance in immune regulation.

Reticuloendotheliosis virus (REV-T) is a replication-defective retrovirus which induces a rapidly-fatal lymphoma. The helper virus, reticuloendotheliosis-associated virus (REV-A), induces a splenic suppressor cell population which cytostatically inhibits the proliferation of cytotoxic cells capable of lysing REV-T tumour cells.

Animals↗
PubMed1983

Induction of stress proteins in Sindbis virus- and vesicular stomatitis virus-infected cells.

Two proteins which are related to certain proteins induced by hyperthermia (heat shock proteins; hsp) are synthesized during lytic infection of chick embryo (CE) cells by Sindbis virus or vesicular stomatitis virus (VSV). Incubation of the infected cells at elevated temperature further increased the rate of synthesis of these proteins. The stress proteins induced by Sindbis virus had different mobilities on SDS-polyacrylamide gels compared to related stress proteins induced in mock-infected CE cells. Induction of the stress proteins in Sindbis virus- and VSV-infected CE cells was actinomycin D sensitive. Kinetic studies indicated that induction of the stress proteins is an early event during infection. The lytic virus-induced selective termination of host protein synthesis did not affect the synthesis of these proteins. Furthermore, the synthesis of these virus-induced stress proteins was resistant, relative to the synthesis of most host proteins, to alterations in the intracellular concentrations of Na+ and K+. The synthesis of a protein related to a major low-molecular-weight hsp of CE cells was not induced after Sindbis virus or VSV infection. Immunoprecipitation experiments and sedimentation analyses demonstrated that significant levels of the capsid protein (C) of Sindbis virus and nucleocapsid protein (N) of VSV are physically associated with a hsp in lysates of infected CE cells.

Amino Acids↗
PubMed1983

Nucleotide sequence of v-rel: the oncogene of reticuloendotheliosis virus.

The nucleotide sequence of v-rel, the oncogene carried by reticuloendotheliosis virus (REV), has been determined. The defective transforming genome REV arose through the insertion of v-rel (1,415 nucleotides) into the env gene of the helper virus REV-A. The predicted rel protein (503 amino acids) employs the REV-A env initiator and terminates within the p20E region of env. Because there are no natural antisera that detect the REV transforming protein, this nucleotide sequence provides the first step toward its isolation and characterization. The predicted protein is clearly distinct from all other reported transforming proteins but may be very distantly related to members of the src family.

Amino Acid Sequence↗
PubMed1983

Specificity in the immunosuppression induced by avian reticuloendotheliosis virus.

Several parameters of the cellular and humoral immune responses of chickens infected with reticuloendotheliosis virus (REV-T), an avian defective acute leukemia virus, or with its helper virus, reticuloendotheliosis-associated virus (REV-A), were evaluated. Spleen cells from chickens infected with REV-T (REV-A) or REV-A exhibited depressed mixed lymphocyte and mitogen responses in vitro. Allograft rejection was delayed by 6 to 14 days in birds infected with REV-A. The specific antitumor cell immune response was also studied by a 51Cr-release cytotoxicity assay. Lymphocytes from chickens infected with low numbers of the REV-T-transformed cells exhibited significant levels of cytolytic reactivity against the 51Cr-labeled REV-T tumor cells in vitro. The mitogen response of lymphocytes from these injected birds was similar to that of uninjected chickens. In contrast, lymphocytes from chickens injected with higher numbers of REV-T-transformed cells exhibited suppressed mitogen reactivity and failed to develop detectable levels of cytotoxic activity directed against the REV-T tumor cells. These results suggest that the general depression of cellular immune competence which occurs during REV-T (REV-A) infection could contribute to the development of this acute leukemia by inhibiting the proliferation of cytotoxic cells directed against the tumor cell antigens. The cytotoxic effect observed after the injection of chickens with non-immunosuppressive levels of REV-T-transformed cells appears to be specific for the REV-T tumor cell antigens since cells transformed by Marek's disease virus or avian erythroblastosis virus were not lysed. In marked contrast, birds whose cellular immune responses were suppressed by infection with REV-A were capable of producing a humoral immune response to viral antigens. Detectable levels of viral antibody, however, did not appear until 12 to 15 days after REV-A infection. Since REV-T (REV-A) induced an acute leukemia resulting in death within 7 to 14 days, it appears unlikely that the ability of chickens to make antiviral antibody influences the development of lethal reticuloendotheliosis.

Animals↗
PubMed1983

Reticuloendotheliosis virus-transformed cells contain infectious and noninfectious proviral sequences in different chromosomes.

The integration site of reticuloendotheliosis virus proviral DNA in the DNA from a cloned reticuloendotheliosis virus-transformed bone marrow cell line was studied. These reticuloendotheliosis virus-transformed bone marrow cells produce a replication-defective transforming virus (REV-T) and a nontransforming helper virus, designated reticuloendotheliosis-associated virus (REV-At). The DNA from this REV-T transformed bone marrow cell line was hybridized with 3H-labeled in vitro synthesized DNA complementary to the reticuloendotheliosis virus (RE) genome to show that these cells contain approximately five genome equivalents per haploid genome. These hybridization experiments did not distinguish between the transforming and nontransforming virus sequences in these cells. Metaphase chromosomes have been isolated from colcemid-treated bone marrow cells and separated into four different size classes on zonal gradients. Hybridization experiment with RE-specific cDNA indicated that all four size classes of chromosomes contain RE-specific sequences. To locate the infectious provirus DNA of the helper virus REV-At, transfection experiments were performed with DNA extracted from the chromosomes of each size class. Infectious REV-At provirus DNA was found principally in one size class. This size class contained the intermediate size macrochromosomes 5 through 11. These results suggest that REV-At proviral DNA must be integrated into a specific chromosome to produce infectious virus.

Animals↗
PubMed1982

Membrane-mediated alterations of intracellular Na+ and K+ in lytic-virus-infected and retrovirus-transformed cells.

Infection of chick-embryo fibroblasts and other cells by certain animal viruses results in alterations in the intracellular concentrations of Na+ and K+. Dramatic alterations in monovalent-cation concentrations of lytic-virus-infected cells may favor the synthesis of viral proteins over cellular proteins. More subtle alterations in retrovirus-transformed cells may result in the expression of many morphological and biochemical changes associated with the transformed phenotype.

Animals↗
PubMed1982

Genome of reticuloendotheliosis virus: characterization by use of cloned proviral DNA.

Reticuloendotheliosis virus is an avian type C retrovirus that is capable of transforming fibroblasts and hematopoietic cells both in vivo and in vitro. This virus is highly related to the three other members of the reticuloendotheliosis virus group, including spleen necrosis virus, but it is apparently unrelated to the avian leukosis-sarcoma virus family. Previous studies have shown that it consists of a replication-competent helper virus (designated REV-A) and a defective component (designated REV) that is responsible for transformation. In this study we used restriction endonuclease mapping and heteroduplex analysis to characterize the proviral DNAs of REV-A and REV. Both producer and nonproducer transformed chicken spleen cells were used as sources of REV proviral DNA; this genome was mapped in detail, and fragments of it were cloned in lambdagtWES.lambdaB. The infected canine thymus line Cf2Th(REV-A) was used as a source of REV-A proviral DNA. The restriction maps and heteroduplexes of the REV and REV-A genomes showed that (proceeding from 5' to 3') (i) REV contains a large fraction of the REV-A gag gene (assuming a gene order of gag-pol-env and gene sizes similar to those of other type C viruses), for the two genomes are very similar over a distance of 2.1 kilobases beginning at their 5' termini; (ii) most or all of REV-A pol is deleted in REV; (iii) REV contains a 1.1 kilobase segment derived from the 3' end of REV-A pol or the 5' end of env or both; (iv) this env region in REV is followed by a 1.9-kilobase segment which is unrelated to REV-A; and (v) the helper-unrelated segment of REV extends essentially all of the way to the beginning of the 3' long terminal repeat. Therefore, like avian myeloblastosis virus but unlike the other avian acute leukemia viruses and most mammalian and avian sarcoma viruses, REV appears to be an env gene recombinant. We also found that the REV-specific segment is derived from avian DNA, for a cloned REV fragment was able to hybridize with the DNA from an uninfected chicken. Therefore, like the other acute transforming viruses, REV appears to be the product of recombination between a replication-competent virus and host DNA. Two other defective genomes in virus-producing chicken cells were also cloned and characterized. One was very similar to REV in its presumptive gag and env segments, but instead of a host-derived insertion it contained additional env sequences. The second was similar (but not identical) to the first in its gag and env regions and appeared to contain an additional 1-kilobase inversion of REV-A sequences.

Animals↗
PubMed1981

Avian reticuloendotheliosis virus: identification of the hematopoietic target cell for transformation.

Non-virus-producing hematopoietic cells transformed in vitro by reticuloendotheliosis virus (REV-T) induce lethal "reticuloendotheliosis" when inoculated into histocompatible chickens. This is the first direct demonstration that an in vivo target cell of an avian acute leukemia virus can be transformed in vitro. The tumorigenic, REV-T-transformed non-virus-producing cells fail to express helper-virus-coded proteins. REV-T transformed tumorigenic cells therefore do not require helper-virus functions. Cells transformed in vivo or in vitro by REV-T have lymphoblastoid morphology and express low levels of terminal-deoxynucleotidyl-transferase activity and bursal-cell determinants. One clone synthesized Ig mu. The preferred target cells for REV-T transformation are therefore immature lymphoid cells that express B-cell determinants. We propose that the unique transforming sequence of REV-T be designated rel (lymphoid).

Animals↗