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H R Bose

Publications and source records attributed to H R Bose.

At least 37 records · Page 2Linked to original sources
PubMed1993

Identification of a rel-related protein in the nucleus during the S phase of the cell cycle.

The c-rel proto-oncogene encodes a 75-kDa protein (p75c-rel) which is present in the cytosol of chick embryo fibroblasts (CEF) associated with a distinct set of cellular proteins with molecular masses of 40, 115, and 124 kDa. CEF cultures arrested in S phase of the cell cycle, or enriched for G2 or mitotic cells, were examined to determine whether the expression of c-rel was altered during the cell cycle. Levels of p75c-rel remained constant in all portions of the cell cycle examined; however, a Rel-related protein with an apparent molecular mass of 64 kDa was detected in nuclei of S-phase cells. As cells enter G2, the level of this protein in the nucleus decreases. This protein reacts with antiserum generated against the carboxy terminus of p75c-rel in radioimmunoprecipitations and Western immunoblot experiments and was also detected in a Western immunoblot with antiserum generated against the first 161 amino acids of pp59v-rel. Thus, unlike other Rel/NF-kappa B family members, p64 has carboxy-terminal homology with c-Rel. The majority of peptides generated by partial proteolytic cleavage of p64 are shared with peptides generated by digestion of p75c-rel and/or pp59v-rel. We suggest that this protein represents a new member of the Rel family of transcription factors and is located in the nucleus of avian fibroblasts during S phase of the cell cycle.

Amino Acid Sequence↗
PubMed1992

Direct association of pp40/I kappa B beta with rel/NF-kappa B transcription factors: role of ankyrin repeats in the inhibition of DNA binding activity.

To understand the mechanism by which pp40/I kappa B beta inhibits DNA binding activity of the rel/NF-kappa B family of transcription factors, we have investigated the role of ankyrin repeats on the biological function of pp40 by deleting or mutating conserved residues. We show that (i) ankyrin repeats alone are not sufficient to manifest biological activity but require the C-terminal region of the pp40 protein; (ii) four out of the five ankyrin repeats are essential for inhibiting the DNA binding activity; (iii) pp40 mutants that do not inhibit DNA binding of rel protein also do not associate with rel; (iv) although pp40 can associate with the p65 and p50 subunits of NF-kappa B, pp40 inhibits the DNA binding activity of only the p50-p65 heterodimer and the p65 homodimer; and (v) pp40 inhibits the transcription of genes linked to kappa B site; however, mutants that do not affect DNA binding have no effect. We propose that the ankyrin repeats and the C-terminal region of pp40 form a structure that associates with the rel homology domain to inhibit DNA binding activity.

Amino Acid Sequence↗
PubMed1992

Alterations within pp59v-rel-containing protein complexes following the stimulation of REV-T-transformed lymphoid cells with zinc.

pp59v-rel exists in association with specific cellular proteins within lymphoid cells transformed by reticuloendotheliosis virus (REV-T). These include the cellular rel homolog (p75c-rel) as well as a 40-kDa avian homolog to I kappa B. The brief exposure of REV-T-transformed lymphoid cells to micromolar concentrations of ZnSO4 induces profound alterations within these protein complexes. Most of the constituents of the rel protein complexes (to include pp59v-rel, p75c-rel, and p115) translocate from the cytosol to the nucleus. This system has been used to characterize the molecular events that accompany the activation of rel protein complexes. The level of phosphorylation increases on three proteins within these complexes: pp59v-rel, p75-c-rel, and pp40. The degree of phosphorylation on pp59v-rel is such that its relative mass increases 3 to 6 kDa when resolved by SDS-polyacrylamide gel electrophoresis. pp59v-rel is phosphorylated on serine and threonine residues predominantly within a single domain of 17.5 kDa. Similarly, p75c-rel exhibits a corresponding increase in its relative mass with increased phosphorylation. The increased phosphorylation of pp40 is accompanied by its dissociation from the cytosolic rel protein complexes. These observations draw parallels with the induction of the NF-kappa B trans-activating factor.

Alkaloids↗
PubMed1991

Rel-associated pp40: an inhibitor of the rel family of transcription factors.

The Rel-associated protein pp40 is functionally related to I kappa B, an inhibitor of the transcription factor NF-kappa B. Purified pp40 inhibits the DNA binding activity of the NF-kappa B protein complex (p50:p65 heterodimers), p50:c-Rel heteromers, and c-Rel homodimers. The sequence of the complementary DNA encoding pp40 revealed similarity to the gene encoding MAD-3, a protein with mammalian I kappa B-like activity. Protein sequencing of I kappa B purified from rabbit lung confirmed that MAD-3 encodes a protein similar to I kappa B. The sequence similarity between MAD-3 and pp40 includes a casein kinase II and consensus tyrosine phosphorylation site, as well as five repeats of a sequence found in the human erythrocyte protein ankyrin. These results suggest that rel-related transcription factors, which are capable of cytosolic to nuclear translocation, may be held in the cytosol by interaction with related cytoplasmic anchor molecules.

Amino Acid Sequence↗
PubMed1991

The v-rel oncogene of avian reticuloendotheliosis virus transforms immature and mature lymphoid cells of the B cell lineage in vitro.

Heavy chain gene rearrangements were analyzed in 67 independently derived reticuloendotheliosis virus (REV-T) transformed avian lymphoid cell lines. The status of the heavy chain genes in these REV-T transformed cell lines was determined, in part, by the age of the chicken whose spleen cells were transformed. Cell lines derived by the in vitro transformation of splenic lymphocytes obtained from embryos did not contain heavy chain gene Ig rearrangements. By contrast, splenic lymphocytes transformed by REV-T obtained from birds 1 week or older generally exhibited heavy chain gene rearrangements. The REV-T transformed lymphoid cell lines with heavy chain rearrangements also had light chain gene rearrangements. The Ig gene rearrangements in REV-T transformed cells were functional. The majority of the cells which had heavy chain rearrangements expressed a 2.2-kb mu transcript and synthesized and secreted IgM. An REV-T transformant was also identified which produced IgG, suggesting that v-rel can transform a terminally differentiated cell. Irrespective of their Ig chain gene status the REV-T transformed cell lines expressed variable amounts of some but not all normal B cell-specific markers and failed to express T cell markers. All the cell lines analyzed expressed the B-L (Ia-like) antigen as well as a common leukocyte antigen. Based on the expression of these surface molecules, the transformants with or without Ig gene rearrangements all appear to be committed to the B cell pathway.

Alleles↗
PubMed1991

The rel-associated pp40 protein prevents DNA binding of Rel and NF-kappa B: relationship with I kappa B beta and regulation by phosphorylation.

The product of proto-oncogene Rel associates with a number of cellular proteins. We have studied the effect of one of them, a phosphoprotein of 40 kD (pp40), on the DNA-binding activity of the Rel protein. We demonstrate that purified pp40 not only inhibits the binding of Rel, but also NF-kappa B (p50-p65) heterocomplex to DNA. Additionally, I kappa B beta, but not I kappa B alpha, also prevented the binding of Rel to the kappa B site. I kappa B beta and pp40 are related proteins because (1) they share a number of common tryptic peptides, (2) their inhibitory effect on DNA binding can be abolished by preincubation with pp40-specific antiserum, and (3) labeled I kappa B beta can be immunoprecipitated with pp40 antibodies. pp40 is part of the Rel complex present in the cytoplasm and nuclear extracts of WEHI-231 cells. The activity of pp40 to inhibit the DNA binding of Rel and NF-kappa B is modulated by phosphorylation.

Animals↗
PubMed1990

The v-rel oncogene product is complexed with cellular proteins including its proto-oncogene product and heat shock protein 70.

The oncogene product, pp59v-rel, of avian reticuloendotheliosis virus (REV-T) is complexed in the cytosol of REV-T transformed lymphoid cells with cellular proteins. Monoclonal antibodies and antisera directed against different regions of pp59v-rel coimmunoprecipitate five cellular proteins (p124, p115, p75, p70, and p40) in addition to pp59v-rel. Cellular proteins with the same apparent molecular mass also copurify with pp59v-rel during sequential Sephacryl S200 and immunoaffinity chromatography. Antisera directed against the most abundant cellular protein in the complex, pp40, coimmunoprecipitate pp59v-rel and several cellular proteins with the same apparent molecular mass. The 75-kDa protein in the pp59v-rel complex is the product of c-rel proto-oncogene and is weakly phosphorylated. In MSB-1 cells this protein is not detectably phosphorylated or associated with cellular proteins. The 70-kDa protein in the pp59v-rel containing cytosolic complex is the constitutive form of avian heat shock protein 70 (HSC70). The p70 protein coimmunoprecipitates and copurifies with pp59v-rel using antisera directed against pp59v-rel and coimmunoprecipitates with antisera specific for pp40. The p70 isolated from immune complexes containing pp59v-rel shares V8 protease fragments with HSC70.

Animals↗
PubMed1990

Identification of protein complexes containing the c-rel proto-oncogene product in avian hematopoietic cells.

The c-rel proto-oncogene product has been identified as a 75 kDa protein expressed in lymphoid cells transformed by REV-T and Marek's disease virus. A 4.0 kb c-rel transcript is expressed in the bursa, spleen and thymus of chickens with highest levels of expression at 10 days post hatch. Using antiserum specific for the v-rel oncogene product, P75c-rel has been precipitated from [35S]methionine-labeled extracts of bursal, splenic and thymic lymphocytes. Additionally, proteins with the molecular mass of 40 kDa, 115 kDa, and 124 kDa co-immunoprecipitate. These proteins co-migrate with the proteins found associated with pp59v-rel in REV-T transformed lymphoid cells. Antiserum specific for pp40, the most abundant cellular protein associated with pp59v-rel, co-precipitates p75c-rel verifying the existence of p75c-rel/pp40 complexes in normal avian lymphocytes. Antiserum directed against the amino-terminal region of pp59v-rel fails to precipitate native p75c-rel complexes from normal lymphoid cells. In the presence of ionic detergents, antisera directed against the amino, middle and carboxy-regions precipitate equivalent amounts of p75v-rel. These results suggest that the amino-terminal region of p75c-rel is active in binding other proteins or is inaccessible to the antiserum due to the conformation of p75c-rel in the complex. Two p75c-rel complexes exist in the cytosol of normal lymphocytes. The most abundant complex contains 60% of the p75c-rel associated with p115 and p124. The remaining p75c-rel is associated with pp40.

Animals↗
PubMed1989

The role of monovalent cation transport in Sindbis virus maturation and release.

Alterations in intracellular monovalent cation concentrations in Sindbis virus-infected avian cells result, in part, from a reduction in Na+/K+ ATPase (Na+ pump) activity. Inhibition of Na+ pump activity was shown previously to temporally correlate with the appearance of viral envelope proteins on the cell surface and the release of virus particles. Cells infected with envelope-defective temperature-sensitive mutants exhibited reduced Na+ pump activity at the nonpermissive temperature, where viral particles are not released. By contrast, Na+ pump activity was not inhibited in Sindbis virus-infected cells treated with tunicamycin or with antiviral serum, which block virus maturation and release. Diuretic-sensitive transport of 86Rb+, aK+ tracer, was stimulated in cells which express virus envelope proteins, but fail to release virus particles. In these cells, the furosemide-sensitive 86Rb+ influx exhibited an increase in Vmax and was responsive to changes in the extracellular concentration of NaCl. Furosemide inhibited the rapid release of virus from low salt-inhibited cells after shift to isotonic conditions. Alterations in ion transport during alphavirus infection may, therefore, facilitate the efficient release of progeny virus particles.

Biological Transport↗
PubMed1989

Oncogenes, protooncogenes, and signal transduction: toward a unified theory?

This paper has reviewed, in a broad sense, the potential involvement of the oncogenes and their progenitors, the protooncogenes, in signal transduction pathways. The membrane-associated oncogene products appear to be connected with the generation and/or regulation of secondary messengers, particularly those associated with Ca2+/phospholipid-dependent activation of the serine/threonine kinase protein kinase C. Activation of transmembrane receptors, either through binding their native ligand or through point mutations that lead to constitutive expression, results in the expression of their intrinsic tyrosine-specific protein kinases. In PDGF-stimulated cells, this results in the increased turnover of phosphatidylinositols and the subsequent release of IP3 (Habenicht et al., 1981; Berridge et al., 1984). This coincides with activation of a PI kinase activity (Kaplan et al., 1987). Likewise, the fms product, which is the receptor for CSF-1, induces a guanine nucleotide-dependent activation of phospholipase C (Jackowski et al., 1986). Receptor functions are potentially regulated through differential binding of ligands (as proposed with PDGF), through interactions with other receptors, and through the "feedback" regulation mediated by protein kinase C. PDGF stimulation leads to modulation of the EGF receptor through protein kinase C (Bowen-Pope et al., 1983; Collins et al., 1983; Davis and Czech, 1985). Similarly, the neu product becomes phosphorylated on tyrosine residues following treatment of cells with EGF, although the neu protein does not bind EGF itself (King et al., 1988; Stern and Kamps, 1988). The tyrosine kinases of the src family are not receptors themselves, although they may mediate specific receptor-generated signals. The clck product is physically and functionally associated with the T-cell receptors CD4 and CD8, and becomes active upon specific stimulation of cells expressing those markers (Veillette et al., 1988a,b). The precise physiological role of the src family products has not been established, but their kinase activity is intrinsic to that function. The v- and c-src products are hyperphosphorylated during mitosis (Chackalaparampil and Shalloway, 1988), which correlates with periods of reduced cell-to-cell adhesion and communication (Warren and Nelson, 1987; Azarnia et al., 1988). Furthermore, pp60c-src is associated with a PI kinase activity when complexed with MTAg of polyoma virus, suggesting a function in stimulating increased turnover of the phosphatidylinositols (Heber and Courtneidge, 1987; Kaplan et al., 1987).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Acquisition of new proviral copies in avian lymphoid cells transformed by reticuloendotheliosis virus.

The expression of the v-rel oncogene of avian reticuloendotheliosis virus (REV-T) transforms and immortalizes very immature avian lymphoid cells. In REV-T-transformed lymphoid cells which were persistently infected with reticuloendotheliosis-associated virus (REV-A), the REV-T proviral copy number increases after the initial integration event. In 23 independently derived REV-T-transformed cell lines, 15 of the 18 virus-producing cell lines had acquired additional proviruses. The rate at which the newly acquired proviral sequences accumulated differed for various cell lines. In some cell lines, additional REV-T proviral copies could be detected as early as 8 months after the initial integration event. A correlation exists between the number of REV-T proviral sequences and the length of time which a given cell line had been propagated in culture. The integration sites occupied by the newly acquired REV-T proviruses were distinct. In contrast, reticuloendotheliosis-associated virus proviral sequences in these REV-T-transformed virus-producing lymphoid cells did not increase during in vitro culture. Furthermore, the acquisition of additional REV-T proviral sequences did not occur in non-virus-producing cell lines. Two of the newly acquired proviral sequences were molecularly cloned and analyzed by restriction endonuclease mapping. Although the newly acquired REV-T proviruses have not sustained major deletions, the viral sequences and the v-rel oncogene display numerous restriction enzyme polymorphisms. The cellular flanking sequences of two newly acquired REV-T proviruses analyzed were unique and shared no homology with flanking sequences of the other REV-T proviruses in these transformed cells. The nucleotide sequence of the virus-cellular DNA junctions of one newly acquired provirus and its cellular sequence prior to proviral integration were defined. A 5-base-pair direct repeat of cellular origin was present on each side of the long terminal repeat, indicating that the mechanism of acquisition of additional REV-T proviral sequences used reverse transcription and integration of new REV-T proviral copies.

Animals↗
PubMed1989

Rearrangement and diversification of immunoglobulin light-chain genes in lymphoid cells transformed by reticuloendotheliosis virus.

Avian lymphoid cells transformed by reticuloendotheliosis virus (REV-T) serve as a model to analyze the mechanism by which B-cell differentiation and antibody diversification occur in birds. Immunoglobulin light-chain gene rearrangements, diversification, and expression were analyzed in 72 independently derived REV-T-transformed cell lines. Lymphoid cells transformed as the result of expression of the v-rel oncogene were divided into two distinct groups based on light-chain gene rearrangements. The status of the light-chain gene loci in these REV-T-transformed cell lines was determined in part by the ages of the chickens whose spleen cells were transformed. In embryonic spleen cell lines transformed by the v-rel oncogene, rearrangements were not detected, even after prolonged culture in vitro, indicating that these cells are arrested in B-cell differentiation. REV-T transformants derived from spleens obtained from chickens 2 weeks old or older, however, had at least one light-chain allele rearranged. All of the cell lines analyzed which exhibited rearranged light-chain genes contained light-chain transcripts, and most of the REV-T-transformed cells which displayed light-chain rearrangements expressed immunoglobulin protein. REV-T, therefore, transforms B-lymphoid cells at phenotypically different stages of development. Many REV-T-transformed cells undergo immunoglobulin chain gene rearrangements during prolonged propagation in vitro. Most of the cell lines which rearrange their light-chain alleles also undergo diversification during cultivation in vitro. Light-chain diversification occurs during or after the rearrangement event.

Aging↗
PubMed1989

Expression of the c-rel and c-myc proto-oncogenes in avian tissues.

Reticuloendotheliosis virus (REV-T) transforms very immature avian lymphoid cells and induces a rapidly fatal lymphoma. The viral oncogene, v-rel, encodes a 59 kDa phosphoprotein which is complexed with cellular proteins in the cytosol of REV-T transformed lymphoid cell lines. The proto-oncogene, c-rel, has been highly conserved among both vertebrate and invertebrate species. The expression of both the c-rel and c-myc protoncogenes was characterized during avian development. Two distinct rel-related transcripts were detected. A 4.0kb mRNA was the principal transcript expressed in cells of hematopoietic origin with highest levels detected in bursa, thymus, and spleen tissue obtained from hatched birds. Relatively low levels of this 4.0 kb transcript were detected in nonhematopoietic tissues. Thus, the distribution of this mRNA correlated with the presence of target cells for transformation by v-rel. The 4.0 kb c-rel transcript had a half-life of nearly 2 h in an avian lymphoid cell line. A second rel-related transcript was identified in the ovary of young hens and appeared to be expressed either in primary oocytes or in the developing follicle. This 2.6 kb c-rel mRNA was detected at substantially lower levels in cells of hematopoietic origin. Using radiolabeled RNA probes, the 2.6 kb c-rel transcript was not detected in liver, brain, testes, or muscle. The c-myc proto-oncogene was also expressed in cells of hematopoietic tissue and ova obtained from hatched birds. While intermediate RNA levels were observed in muscle and liver cells, the c-myc gene was not expressed in avian testes.

Actins↗
PubMed1988

Serine phosphorylation of the v-rel oncogene product/pp40 complex.

The transforming protein encoded by the v-rel oncogene of reticuloendotheliosis virus has been purified from REV-T transformed lymphoid cells by sequential DEAE-Sepharose and immunoaffinity chromatography. The purified preparation consisted of pp59v-rel and the 40 kDa cellular protein which is complexed with the v-rel oncogene product in transformed cells as well as some minor proteins. Incubation of this purified preparation in the presence of Mg2+ and (gamma-32P)ATP resulted in phosphorylation of both pp59v-rel and the 40 kDa protein. This preparation was also able to phosphorylate casein on serine residues. Immunoprecipitates obtained from extracts of REV-T transformed lymphoid cells labeled with 32P-orthophosphate contained 59 and 40 kDa phosphoproteins. Both pp59v-rel and the 40 kDa protein were phosphorylated on serine residues in transformed cells.

Adenosine Triphosphate↗
PubMed1988

Autogenous growth factor production by reticuloendotheliosis virus-transformed hematopoietic cells.

Reticuloendotheliosis virus strain T (REV-T)-transformed cells gave rise spontaneously to variants which secrete a factor that forms a distinct visible ring of precipitation (halo) surrounding colonies grown in soft agar. An Mr 15,000 protein was produced at higher levels by halo variants than by nonhalo-producing cells. An assay designed to detect the formation of precipitates enabled purification of an Mr 15,000 protein, p15, from serum-free medium conditioned by the growth of REV-T-transformed hematopoietic cells. Fractions enriched in p15 permitted the growth of REV-T-transformed cells under conditions where they normally failed to proliferate.

Animals↗
PubMed1988

Expression of the v-rel oncogene in reticuloendotheliosis virus-transformed fibroblasts.

Reticuloendotheliosis virus (REV-T) induces a rapidly fatal lymphoma in chickens through the expression of its oncogene, v-rel, REV-T also morphologically transforms avian fibroblasts in vitro. These transformed cells displayed limited anchorage-independent growth and reached higher saturation density than uninfected or REV-A-infected fibroblasts. Morphologically transformed fibroblasts were tumorigenic when injected into the wing web of chickens. In transformed fibroblasts, the v-rel oncogene was expressed as a 57 kDa phosphoprotein with a half-life of 2 to 4 hr. A cellular phosphoprotein of about 40 kDa was also observed in immunoprecipitates of transformed fibroblasts. The subcellular location of the v-rel-encoded protein was determined using cell fractionation procedures and immunofluorescent staining. In acutely infected, nontransformed fibroblasts, pp57v-rel was associated with the nuclear region, but in morphologically transformed cells the v-rel protein was found in the cytoplasm. These observations suggest that the expression of the v-rel oncogene is insufficient for transformation and that the cellular localization of this transforming protein to the cytoplasm may be required for the progression to an altered cell phenotype in avian fibroblasts.

Alpharetrovirus↗