| glucocorticoid regulation of mouse mammary tumor virus gene expression. | glucocorticoid hormones act rapidly and specifically to stimulate the synthesis of mouse mammary tumor virus rna in a variety of mouse mammary tumor cells and infected heterologous cells. the increase in viral rna production appears to be mediated by receptor proteins and requires the presence of basal levels of viral rna. infection of heterologous cells with mmtv may alter host cell responses to glucocorticoids; in addition, production of unintegrated viral dna in these cells has provided reage ... | 1979 | 229906 |
| viral expression and immunogenicity of cba mammary carcinomas and their hybrid lines with an l-cell derivative (a9ht). | | 1979 | 230057 |
| detection of virus antigens in swiss albino mice infected by milk-borne mouse mammary tumour virus: the effect of age, sex and reproductive status. i. localization by immunofluorescence of four antigens in mammary tissues and other organs. | the indirect immunofluorescence technique was used to investigate the expression of virus antigens in a swiss albino mouse strain infected by mouse mammary tumour virus (mmtv). the antisera used were monospecific for: the glycopolypeptides gp160 and gp47, and the internal polypeptides p28 and p8. in mice infected with milk-borne mmtv, all four antigens were detected in the mammary gland during the first pregnancy and then throughout life, and in mammary tumours. antigen gp160, located at the sec ... | 1979 | 230308 |
| detection of virus antigens in swiss albino mice infected by milk-borne mouse mammary tumour virus: the effect of age, sex and reproductive status. ii. radioimmunoassay of two virus components, gp47 and p28 in serum and organ extracts. | extracts of various organs, mammary tumours and sera from milk-borne mmtv infected swiss albino mice of different age, sex and physiological conditions were tested by radioimmunoassay for the presence of gp47, the main envelope polypeptide, and p28, the main core protein of the virus. except in brain, ovaries and testes, both antigens were found in all organs of old animals and of females after the onset of their first pregnancy. antigens were not present in organs of weanlings or in whole foetu ... | 1979 | 230309 |
| conditions for hormone-stimulated expression of endogenous c57bl strain-associated mammary tumor virus genome. | full mmtv-y gene expression can occur in dexamethasone-insulin-prolactin-stimulated cell cultured derived from c57bl/10 mammary adenocarcinomas induced by syncarcinogenic action of chemical carcinogens (dimethylbenzanthracene), and mammotropic hormones (estrogen and prolactin). the rate of the hormone-stimulated virus production, as determined by biochemical, immunological and electron microscopical methods, was comparable to the level of spontaneous mmtv production by cells of established mouse ... | 1979 | 230421 |
| envelope antigens of oncoviruses. | | 1979 | 230728 |
| in vivo and in vitro phosphorylation of murine mammary tumour virus proteins. | a comparative study of in vitro and in vivo phosphorylation of murine mammary tumour virus, a type brna virus, is reported. the protein kinase activity associated with murine mammary tumour virus catalysed the in vitro phosphorylation of endogenous virus polypeptides. this kinase activity required a divalent metal cation, a non-ionic detergent, and was stimulated in the presence of dithiothreitol. exogenous cyclic amp was not required. the 32p-labelled products of the in vitro reaction were comp ... | 1979 | 231088 |
| biological behaviour of two sublines of mammary cancer susceptible strains made free of mammary tumour virus (mtv) by foster-nursing. | | 1978 | 232065 |
| molecular relationship of the dna and rna of intracytoplasmic a particles to mouse and mammary tumour virus genomes. | we have directly tested the hypothesis that single-stranded cytoplasmic a particle-associated dna (ss cap dna) is a murine mammary tumour virus (mmtv) proviral intermediate by hybridizing 125i-labelled ss cap dna to mmtv rna or to mmtv complementary dna (cdna). 125i-labelled cap dna did not form duplexes with either mmtv rna or mmtv cdna. in contrast, cap rna hybridized readily with mmtv cdna. cap rna contained all the mmtv virus sequences, but at lower concentrations than in mmtv virus particle ... | 1979 | 232129 |
| impaired maturation of mouse mammary tumor virus precursor polypeptides in lymphoid leukemia cells, producing intracytoplasmic a particles and no extracellular b-type virions. | processing of polypeptides of the mouse mammary tumor virus, a type b retrovirus, was investigated in a transplanted thymic lymphoma cell line of the gr strain (grsl). this cell line was maintained in vivo in ascites form and in vitro as a suspension culture. grsl cells produce clusters of intracytoplasmic a particles and are virtually deficient in the production of mature extracellular b-type particles. as control, a mammary tumor cell line of the same mouse strain capable of complete virion sy ... | 1979 | 232176 |
| [leukemogenic activity of cell-free centrifugates of a transplantable mammary gland adenocarcinoma in cc56br strain mice]. | | 1979 | 232258 |
| bioactivities and the effect of dilution on various milk-borne murine mammary tumor viruses. | infectivity titrations of milk-borne murine mammary tumor virus (mumtv) from different sources or prepared in different ways or stored for periods of time have been compared. titration curves were in general reproducible for mumtvs of different sources or handled in different ways and for different methods of measurement, such as hyperplastic alveolar nodule (han) development, tumor development, or mumtv antigen secretion in third-lactation milk, the curves had characteristic shapes with a low i ... | 1979 | 232494 |
| tumours of the mammary gland. | | 1979 | 233006 |
| virus precursor shedding from mammary tumour cells. | | 1979 | 233256 |
| is there a role for actin in virus budding? | electrophoretic data from both sodium dodecyl sulfate-polyacrylamide gels (sds-page) and acid-urea gels reveal a protein in purified murine mammary tumor virus (mumtv) which co-migrates with purified chick skeletal muscle actin. 125i-labeling of intact and disrupted virus preparations shows that the actin-like protein is not artifactually adsorbed to the outside of virions during isolation. quantitative sds-page and examination of negatively stained preparations show that the actin cannot be acc ... | 1977 | 233748 |
| leukocyte migration inhibition response to breast cancer antigens and to mouse mammary tumor virus in women with primary breast cancer. | | 1978 | 233830 |
| purification and characterization of the dna polymerase of human breast cancer particles. | previous studies have identified human breast tumor particles possessing many of the features characteristic of rna tumor viruses. in addition to the expected size (600 s) and density (1.16 g/ml) these include possession of an outer membrane and an inner one surrounding a "core" containing a dna polymerase and a large-molecular-weight (70s) rna possessing detectable homology to the rnas of the mouse mammary tumor virus (mmtv) and of the mason-pfizer monkey virus (mpmv). we report here the purifi ... | 1977 | 265540 |
| immunologic techniques for the identification of virion and cell surface antigens by correlative fluorescence, transmission electron and scanning electron microscopy. | the present resolution (75-100 a) of the conventional scanning electron microscope (sem) and its ability to image the surfaces of large numbers of whole cells in situ permits the approach of problems such as viral and cell surface antigen localization by immunological labeling with visual markers. identification of virus and cell surface antigens in situ has been accomplished in indirect reactions by conjugated and unconjugated markers. hemocyanin (hcy) from whelk, busycon canniculatum, has been ... | 1979 | 392719 |
| in vitro mouse mammary tumor virus transcription from chromatin. a system to study the mechanism of action of glucocorticoid hormones. | | 1977 | 563804 |
| tumour incidence, growth, reproduction and longevity in female c3h mice fed polyunsaturated ruminant-derived foodstuffs. | earlier studies with the random-bred quackenbush mouse strain showed that human-type diets based on linoleic acid-enriched foodstuffs derived from ruminants fed protected polyunsaturated oils have no detrimental effects on growth, reproduction or longevity. tumour incidence and time of onset of tumour development have now been studied in the inbred, tumour-prone mouse strain c3h, in addition to growth, reproduction and longevity. mice were fed a polyunsaturated human diet, a conventional human d ... | 1979 | 574381 |
| human antibodies binding to the mouse mammary tumor virus: a nonspecific reaction? | specific rabbit antisera and over 100 human sera were found to precipitate iodinated mouse mammary tumor virus (mtv). the specificity of these reactions was tested in competitive inhibition studies. three classes of reaction could be distinguished. the class 1 reaction was the most specific; it could be inhibited only by mtv and was observed exclusively with rabbit anti-mtv. the class 2 reaction was apparently against mouse cell determinants; it could be inhibited not only by mtv but also by mou ... | 1976 | 943235 |
| spironolactone, an aldosterone antagonist, acts as an antiglucocorticosteroid on the mouse mammary tumor virus promoter. | the ability of the glucocorticosteroid receptor to bind mineralocorticosteroids suggests that spironolactone, a potent aldosterone antagonist, may also interact with the glucocorticosteroid receptor, resulting in an agonist or antagonist glucocorticosteroid activity. we have investigated the effect of this drug on the activity of the glucocorticosteroid-regulated mouse mammary tumor virus (mmtv) promoter. for these studies we used the mouse fibroblast cell line 1471.1. it contains about 200 copi ... | 1992 | 1309341 |
| stroma is critical for preventing or permitting immunological destruction of antigenic cancer cells. | inoculated immunogenic cancer cells after initial growth are potentially rejected by specific host immunity; however, the outcome of the interaction between host and inoculated cancer cells is a function of multiple factors including the route of inoculation, the number of cells, the density of antigens on the injected cancer cells, and the state of the immune system of the host. in the present study, we have examined a different kind of variable: the stroma that inoculated tumor cells initially ... | 1992 | 1309851 |
| the open reading frames in the 3' long terminal repeats of several mouse mammary tumor virus integrants encode v beta 3-specific superantigens. | mice expressing the minor lymphocyte stimulation antigens, mls-1a, -2a, or -3a, singly on the b10.br background have been generated. mls phenotypes correlate with the integration of mouse mammary tumor viruses (mtv) in the mouse genome. the open reading frames within the 3' long terminal repeats of the integrated mtvs 1, 3, 6, and 13 encode v beta 3-specific superantigens. sequence data for these viral superantigens is presented, indicating that it is the cooh-terminal portion of the viral super ... | 1992 | 1309854 |
| an rna pseudoknot and an optimal heptameric shift site are required for highly efficient ribosomal frameshifting on a retroviral messenger rna. | synthesis of the pol gene products of most retroviruses requires ribosomes to shift frame once or twice in the -1 direction while translating gag-pol mrna. the viral signals for frameshifting include a heptanucleotide sequence on which the shift occurs and higher-order rna structure just downstream of the shift site. we have made site-directed mutations in two stems (s1 and s2) of a putative rna pseudoknot that begins 7 nucleotides 3' of the previously identified shift site (a aaa aac) in the ga ... | 1992 | 1309954 |
| superantigens and endogenous retroviruses: a confluence of puzzles. | | 1992 | 1310360 |
| down-regulation of beta-adrenergic receptors by pindolol in gs alpha-transfected s49 cyc- murine lymphoma cells. | the role of the alpha subunit of the guanine nucleotide-binding regulatory protein that stimulates adenylyl cyclase (gs alpha) in the down-regulation of beta-adrenergic receptors by pindolol was studied in s49 cyc- cells (normally gs alpha-deficient) transfected to express functional recombinant rat gs alpha. an inducible cell line (s49 gs alpha ind) was derived from s49 cyc- cells transfected with a vector containing the full-length coding sequence of gs alpha under the inducible control of the ... | 1992 | 1310718 |
| vitamin b6 modulates transcriptional activation by multiple members of the steroid hormone receptor superfamily. | recent studies have shown that vitamin b6 modulates transcriptional activation by the human glucocorticoid receptor in hela s3 cells. we have now examined the possibility that vitamin b6 might similarly influence transcriptional activation by the glucocorticoid receptor in other cell types, as well as gene expression mediated by other members of the steroid hormone receptor superfamily. we show that elevated vitamin b6 concentrations suppress by 40-65% the level of transcription mediated through ... | 1992 | 1310983 |
| structural analysis of a mouse mammary tumor virus superantigen. | it has recently been shown that the minor lymphocyte stimulating-like products expressed by some mice are actually encoded by open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses. these products act as viral superantigens (vsags). that is, they stimulate most t cells bearing particular v beta s almost regardless of the rest of the variable components of the t cell receptors expressed by those cells. to find out more about the structure of these vsags, a set of trunc ... | 1992 | 1311018 |
| the transcriptionally-active mmtv promoter is depleted of histone h1. | we have used an ultraviolet light cross-linking and immunoadsorption assay to demonstrate that histones h1 and h2b are bound to the repressed mmtv promoter. hormone activation results in reduced h1 content with little or no change in h2b. high resolution analysis of the glucocorticoid-inducible dnasei hypersensitive region demonstrates an nf-1 footprint as well as specific sites of enhanced cleavage on nucleosome b and in the nucleosome b/nucleosome a linker. these results are consistent with a ... | 1992 | 1311071 |
| hla-dq beta chain can present mouse endogenous provirus mtv-9 product and clonally delete tcr v beta 5+ and v beta 11+ t cells in transgenic mice. | the elusive mls gene(s) are mouse mammary tumor virus genes. the endogenous cotolerogen involved in the clonal deletion of tcr v beta 5.1, 5.2, and 11 in h-2e+ mouse strains has been narrowed down to mtv-9. we demonstrate that similar to h-2e alpha molecules, human dqw6 beta chain mediated clonal deletion of tcr v beta 5.1, 5.2, and 11 also requires the mtv-9 gene product. this shows that human class ii molecules can present mouse retroviral antigen. further, backcross analysis involving [b10.m( ... | 1992 | 1311702 |
| evidence that nucleosomes on the mouse mammary tumor virus promoter adopt specific translational positions. | we have previously demonstrated that an array of six nucleosomes are phased on the mouse mammary tumor virus (mmtv) long terminal repeat (1,2). in this study, we devised a new assay to measure the translational positions of specific nucleosomes on the mmtv promoter. nucleosome core particles were purified and shown to contain a and b nucleosomal dna by taq polymerase primer extension with nucleosome-specific primers. the 5' and 3' boundaries of a and b nucleosomes were measured by extending to t ... | 1992 | 1311832 |
| induction of mammary tumors by expression of polyomavirus middle t oncogene: a transgenic mouse model for metastatic disease. | the effect of mammary gland-specific expression of the polyomavirus middle t antigen was examined by establishing lines of transgenic mice that carry the middle t oncogene under the transcriptional control of the mouse mammary tumor virus promoter/enhancer. by contrast to most transgenic strains carrying activated oncogenes, expression of polyomavirus middle t antigen resulted in the widespread transformation of the mammary epithelium and the rapid production of multifocal mammary adenocarcinoma ... | 1992 | 1312220 |
| heat shock alters the composition of heteromeric steroid receptor complexes and enhances receptor activity in vivo. | under normal cellular conditions, human progesterone receptors (pr), immune-isolated from cytosols of t47d breast cancer cells, associate with two heat shock proteins (hsps), hsp 90 and hsp 70. receptors activated by hormone binding in vivo and extracted from nuclei with 0.5 m nacl no longer associate with hsp 90 but retain association with hsp 70. we have examined the effect of heat shock treatment of cells on hsp-receptor interactions and on receptor function. heat shock resulted in a partial ... | 1992 | 1312348 |
| v beta repertoire in rats and implications for endogenous superantigens. | endogenous superantigens of mice, encoded by mammary tumor virus proviral integrants, induce intrathymic deletion of entire t cell populations that express specific v beta gene products, a phenomenon proposed to be important in self-tolerance and prevention of toxic responses to exogenous microbial superantigens. evidence for the presence of v beta selecting/deleting endogenous superantigens in other species is lacking. we report here that rats do not exhibit endogenous superantigen-induced v be ... | 1992 | 1312471 |
| biochemical analysis of the mouse mammary tumor virus long terminal repeat product. evidence for the molecular structure of an endogenous superantigen. | recent reports have shown that both exogenous and endogenous mouse mammary tumor viruses (mmtv) can encode superantigens. transfection and transgenic studies have identified the open reading frame (orf) present in the 3' long terminal repeat (ltr) as encoding superantigen function. in this study, we have used an in vitro translation system in an attempt to characterize the molecular nature of the protein encoded by the 3' orf of mtv-8. using various constructs encoding full-length and truncated ... | 1992 | 1312476 |
| mouse mammary tumor gene int-3: a member of the notch gene family transforms mammary epithelial cells. | expression of a 2.3-kb rna species is induced in mammary tumors as a consequence of insertional mutagenesis at the int-3 locus by the mouse mammary tumor virus. the nucleotide sequence and biological activity of this mammary tumor-specific int-3 rna species were determined. it contains an open reading frame which encodes a 57-kda protein. the translated protein possesses six nearly contiguous 32-amino-acid repeats which are related to a similar motif in the saccharomyces cerevisiae cdc-10-encode ... | 1992 | 1312643 |
| a novel intermediate in processing of murine leukemia virus envelope glycoproteins. proteolytic cleavage in the late golgi region. | the intracellular processing of the murine leukemia virus envelope glycoprotein precursor pr85 to the mature products gp70 and p15e was analyzed in the mouse t-lymphoma cell line w7mg1. kinetic (pulse-chase) analysis of synthesis and processing, coupled with endoglycosidase (endo h) and neuraminidase digestions revealed the existence of a novel high molecular weight processing intermediate, gp95, containing endo h-resistant terminally glycosylated oligosaccharide chains. in contrast to previousl ... | 1992 | 1313032 |
| intracellular amplification of proviral dna in tissue sections using the polymerase chain reaction. | we developed a new method to amplify cell dna in situ using the polymerase chain reaction (pcr). proviral sequences of mouse mammary tumor virus (mmtv) contained in cultured cells and tissue sections were amplified intracellularly using a thermal cycler. two techniques were employed to maintain the localization of the amplified dna. first, complementary tails at the 5' ends of the oligonucleotide primers resulted in the synthesis of high molecular weight concatamers containing the target sequenc ... | 1992 | 1313061 |
| transcriptional control by steroid hormones. | gene regulation by steroid hormones leads to induction or repression of particular sets of genes. these effects are mediated by intracellular hormone receptors that, in the unliganded state, are maintained in an inactive form by unknown mechanisms possibly involving association with other cellular proteins. induction of the mouse mammary tumor virus (mmtv) requires binding of the hormone receptor to a complex hormone-responsive element (hre) located between 75 and 190 bp upstream from the start ... | 1992 | 1314074 |
| glucocorticoids in malignant lymphoid cells: gene regulation and the minimum receptor fragment for lysis. | we have examined clones of human malignant lymphoid cells for markers that correlate with glucocorticoid-mediated cell lysis. in glucocorticoid-sensitive clones of cem, a human t-cell lymphoblastic leukemia line, two genes correlate with glucocorticoid-induced cell lysis. the glucocorticoid receptor (gr) itself is induced by standard glucocorticoids in sensitive clones and not in insensitive clones. the phenylpyrazolo-glucocorticoid cortivazol (cvz) is capable of lysing several clones resistant ... | 1992 | 1314075 |
| overexpression of the glucocorticoid receptor represses transcription from hormone responsive and non-responsive promoters. | the glucocorticoid receptor (gr) is a regulable transcription factor which can bind to dna response elements in the vicinity of inducible gene promoters and enhance the rate of transcription initiation. the concentration of endogenously expressed gr has been shown to limit the magnitude of the transcriptional induction response in cultured cells. we have investigated the consequence of increased gr expression on the transcriptional activity of a hormone responsive promoter, the mmtv ltr, and on ... | 1992 | 1314076 |
| v beta 17 t-cell deletion by endogenous mammary tumor virus in wild-type-derived mouse strain. | the wild-type-derived mouse strain pwk possesses a beta-chain variable region v beta 17a2 allele, which is expressed on mature t cells as part of the t-cell receptor of most mice expressing i-e, whereas v beta 17 t cells are deleted in all i-e+ laboratory mice bearing a v beta 17a1 allele. however, (pwk x cba/j)f1 progeny and the wild-type-derived mouse strain mai, which possesses the v beta 17a2 allele, display deletion of v beta 17 t cells. analysis of (pwk x cba/j) x pwk and of (pwk x mai) x ... | 1992 | 1314381 |
| disruptions in intracellular membrane trafficking and structure preclude the glucocorticoid-dependent maturation of mouse mammary tumor virus proteins in rat hepatoma cells. | we have previously shown that glucocorticoids regulate the trafficking and processing of mouse mammary tumor virus (mmtv) proteins in viral-infected m1.54 rat hepatoma cells. to examine the role of intracellular membrane integrity on mmtv protein maturation, brefeldin a (bfa) was utilized to disrupt membrane flow between the endoplasmic reticulum and golgi. immunoprecipitation and immunofluorescence microscopy revealed that in the presence of dexamethasone, bfa inhibited the proteolytic processi ... | 1992 | 1314817 |
| immunosuppression by the mmtv superantigen? | | 1992 | 1315554 |
| [review: transmission of mouse mammary tumor virus (mtv) and its tumorigenesis--comparison between mouse mammary tumor system and human breast cancer]. | | 1992 | 1315689 |
| distinctive patterns of hyperplasia in transgenic mice with mouse mammary tumor virus transforming growth factor-alpha. characterization of mammary gland and skin proliferations. | eight lines of transgenic mice expressing a mouse mammary tumor virus (mmtv) human transforming growth factor-alpha (tgf alpha) fusion gene were established. three lines with distinctive phenotypes are presented. all have proliferative changes of the mammary gland. one line has sebaceous gland hyperplasia of the skin. five histologic patterns of mammary gland hyperplasia based on two of these lines were identified: cystic hyperplasia, solid hyperplasia, dysplasia, adenoma, and adenocarcinoma. hu ... | 1992 | 1316084 |
| the mouse mammary tumour virus long terminal repeat encodes a type ii transmembrane glycoprotein. | superantigens are products of bacterial or viral origin which stimulate large numbers of t cells as a consequence of the interaction of particular v beta chains of the t cell receptor with class ii major histocompatibility complex (mhc) molecules and superantigen on the stimulating cell. the minor lymphocyte stimulatory (mls) antigens, originally discovered as strong lymphocyte stimulatory determinants in vitro and subsequently shown to delete t cells expressing specific v beta chains during dev ... | 1992 | 1316276 |
| efficient production of human immunodeficiency virus proteins in transgenic mice. | transgenic mice containing the complete human immunodeficiency virus (hiv) coding sequences fused to the mouse mammary tumor virus long terminal repeat were generated. they were found to produce high levels of authentic gag and env hiv proteins in several tissues known to support mouse mammary tumor virus-driven transcription. hiv proteins were also detected in serum and in body fluids (milk and epididymal secretions) known to be natural sites of retrovirus, and specifically of hiv, production. ... | 1992 | 1316490 |
| amino acid substitutions in the dna-binding domain of the human androgen receptor are a frequent cause of receptor-binding positive androgen resistance. | in some subjects with genetic and endocrine evidence of androgen resistance, no defect is demonstrable in the binding of androgen to its receptor in cultured genital skin fibroblasts. we have defined the molecular defect in the androgen receptor in four unrelated subjects in this category (termed receptor positive) with the phenotype of compete or incomplete testicular feminization. in these patients we detected amino acid substitutions in either exon 2 or exon 3, which encodes the dna-binding d ... | 1992 | 1316540 |
| the effect of glucocorticoid on the subcellular localization, oligomerization, and processing of mouse mammary tumor virus envelope protein precursor pr74. | mouse lymphoma cell line w7mg1 is stably infected with mouse mammary tumor virus and produces the viral envelope glycoprotein precursor pr74, but the mature envelope proteins gp52 and gp33, which are derived from pr74 by posttranslational processing, are produced only when the cells are cultured with a glucocorticoid agonist. the current study demonstrated that even when w7mg1 cells are grown with hormone, the conversion of pr74 to gp52 and gp33 is an inefficient process in this cell line. at le ... | 1992 | 1316542 |
| two different genes coding for processable and nonprocessable forms of a viral envelope protein can account for the apparent hormonal stimulation of protein processing in w7mg1 lymphoma cells. | in the mouse mammary tumor virus (mmtv)-infected mouse t-lymphoma cell line w7mg1, glucocorticoid hormone regulates two aspects of mmtv gene expression: hormone stimulates mmtv gene transcription and increases the ratio of mature envelope proteins to envelope precursor protein produced. to separate these two effects and determine the mechanism by which hormone regulates the conversion of the envelope precursor pr74 to the mature cleaved products gp52 and gp33, we constructed expression vectors i ... | 1992 | 1316543 |
| effects of hormone and cellular modulators of protein phosphorylation on transcriptional activity, dna binding, and phosphorylation of human progesterone receptors. | human progesterone receptors (pr) in t47d breast cancer cells are synthesized as two different sized proteins, pr-a [94 kilodaltons (kda)] and pr-b (120 kda). progestin addition to cells (in vivo) causes a 2-fold increase in total phosphorylation of pr and an increase in the apparent mol wt of both pr-a and pr-b on sodium dodecyl sulfate (sds)-gels. time-course experiments showed that increased pr phosphorylation that results from hormone addition is a multistep process and involves a rapid incr ... | 1992 | 1316549 |
| fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor. | peroxisome proliferators such as clofibric acid, nafenopin, and wy-14,643 have been shown to activate ppar (peroxisome proliferator-activated receptor), a member of the steroid nuclear receptor superfamily. we have cloned the cdna from the rat that is homologous to that from the mouse [issemann, i. & green, s. (1990) nature (london) 347, 645-650], which encodes a 97% similar protein with a particularly well-conserved putative ligand-binding domain. to search for physiologically occurring activat ... | 1992 | 1316614 |
| transgenic mouse mammary tumor virus superantigen expression prevents viral infection. | endogenous mouse mammary tumor virus (mmtv) proviruses have recently been shown to cosegregate genetically with the minor lymphocyte-stimulating loci, also termed self-superantigens. the antigenic activity has been localized to the open reading frame (orf) protein encoded in the long terminal repeat of mmtv. we show here that unlike their nontransgenic littermates, transgenic mice expressing high levels of an orf protein derived from the c3h exogenous mmtv specifically delete their v beta 14+ t ... | 1992 | 1316806 |
| mls-1-like superantigen in the ma/myj mouse is encoded by a new mammary tumor provirus that is distinct from mtv-7. | mls-1 is an endogenous superantigen that leads to in vivo deletion and in vitro stimulation of t cell receptor (tcr) v beta 6-, 7-, 8.1-, and 9-expressing cells. the ma/myj mouse deletes the identical set of tcr from its mature t cell repertoire; however, it does not contain mtv-7, the murine mammary tumor provirus (mmtv), whose sag gene encodes mls-1. interestingly, the superantigen activity of this mouse strain segregates with a new mammary tumor provirus, mtv-43, not seen in other inbred stra ... | 1992 | 1316931 |
| an exogenous mouse mammary tumor virus with properties of mls-1a (mtv-7). | the classical minor lymphocyte stimulating (mls) antigens, which induce a strong primary t cell response in vitro, are closely linked to endogenous copies of mouse mammary tumor viruses (mmtv). expression of mls genes leads to clonal deletion of t cell subsets expressing specific t cell receptor (tcr) v beta chains. we describe the isolation and characterization of a new exogenous (infectious) mmtv with biological properties similar to the mls antigen mls-1a. in vivo administration of either mls ... | 1992 | 1316932 |
| factors controlling the expression of mouse mammary tumour virus. | | 1992 | 1317161 |
| inhibition of interferon-gamma- and phorbol ester-induced hla-dr and interleukin-1 production by the expression of a transfected poly(adp-ribose) synthetase gene in human leukemia thp-1 cells. | we have examined a correlation between an expression level of poly(adp-ribose) synthetase gene and the stage of monocytic differentiation. we selected three human leukemia cell lines, u937, thp-1, and j111, whose differentiation stage was characterized by nitroblue tetrazolium reduction activity, non-specific esterase activity, phagocytic activity and a cell surface marker. enzyme activity and mrna level of the synthetase decreased in accompaniment with the progress of monocytic differentiation. ... | 1992 | 1317213 |
| int-2, an autocrine and/or ultra-short-range effector in transgenic mammary tissue transplants. | previous studies have shown associations between overexpression of int-2 messenger rna (mrna) and murine mammary tumors and between amplification of the int-2 genomic locus and human breast cancers. the int-2 protein (fibroblast growth factor 3) is a member of the heparin-binding growth factor family of proteins. the export of these growth factors from cells may depend on the presence of amino terminal sequences containing hydrophobic signal peptides. although int-2 has a putative signal sequenc ... | 1992 | 1317463 |
| effects of alprazolam on the development of mtv-induced mammary tumors in female mice under stress. | female c3h/he mice carrying the mammary tumor virus (mtv) were monitored for mammary tumor incidence and latent periods while subjected to a daily intraperitoneal (i.p.) injection of placebo or alprazolam (1 mg/kg per day). although all of the mice were potential candidates for mtv-induced breast cancer, those injected with alprazolam were partially protected against adverse effects of stress induced by the daily administration of placebo. | 1992 | 1317744 |
| androgen-responsive expression and mitogenic activity of schwannoma-derived growth factor on an androgen-dependent shionogi mouse mammary carcinoma cell line. | we report here, using the androgen-dependent sc2g cell line derived from shionogi mouse mammary carcinoma sc115, that cdna encoding mouse homologue of the rat schwannoma-derived growth factor (sdgf) was isolated and its protein product was identified to be an autocrine growth factor which is expressed in response to androgen in this hormone-dependent cell line. the androgen-independent sc1g cells derived from sc115 were shown to express sdgf even in the absence of androgen, while northern analys ... | 1992 | 1318038 |
| expression pattern of mouse mammary tumor virus in transgenic mice carrying exogenous proviruses of different origins. | to study the tissue specificity of mouse mammary tumor virus (mmtv) gene expression, we developed two series of transgenic mice, containing the mmtv proviral dna of mammary (gr) and kidney (c3h-k) origin. the expression pattern in the mmtv(gr) transgenic mice is very similar to that observed in infected animals, e.g., a strong preference for viral expression in the lactating mammary glands and lower levels of expression in salivary glands, lymphoid tissues, and male reproductive organs. one line ... | 1992 | 1318420 |
| maturation of mouse mammary tumor virus envelope protein is blocked by a specific point mutation. | expression of a mouse mammary tumor virus (mmtv) envelope gene, env2, in cos-7 cells resulted in the synthesis of a precursor protein pr74 that underwent complete proteolytic processing to the mature envelope species gp52 and gp33. in contrast, expression of a second mmtv envelope gene, env1, in cos-7 cells resulted in the synthesis of a precursor protein pr74 that failed to undergo proteolytic processing to the mature products. expression and sequencing of various chimeric env1/env2 genes deter ... | 1992 | 1318614 |
| molecular characterization of mls-1. | recently a series of endogenous and exogenous superantigens have been described which have one common feature, namely, they lead to in vivo deletion and in vitro stimulation of t cells expressing particular t cell receptor v beta genes. the mls antigens represent the prototypes of these molecules. we have mapped mls-1 to the endogenous mammary tumor virus (mmtv) mtv-7, while other sag have also been associated with various mmtv. the open reading frame gene of the mmtv encodes the sag. thus, the ... | 1992 | 1318934 |
| endogenous ligands selecting t cells expressing particular v beta elements. | it has recently become clear that the minor lymphocyte stimulatory antigens (mls) and other endogenous ligands which lead to the partial or total deletion of t cells bearing particular v beta segments are encoded by mouse mammary tumor virus (mmtv). we review here the genetic analyses of multiple v beta 11 and v beta 3 deletion ligands and demonstrate the involvement of mmtv in all examples. several features of mls and the v beta 11/v beta 3 deleting ligands identify them as members of the super ... | 1992 | 1318935 |
| retroviral super-antigens and t cells. | for many years immunologists have been intrigued by a series of potent antigens encoded in the murine genome. these antigens, originally termed minor lymphocyte stimulating (mls) antigens, are capable of inducing extremely strong t cell proliferative responses when presented in the context of mhc class ii molecules. recently, mls antigens have been shown to stimulate t cells bearing particular t cell receptor v beta elements, leading to the designation of super-antigens. the endogenous expressio ... | 1992 | 1318936 |
| expression of the mouse mammary tumor virus orf gene in cultured cells. | we have recently shown that expression vectors harboring the open reading frame of the long terminal repeat region of mouse mammary tumor virus direct the synthesis of a product which acts as a superantigen in transgenic mice. the detection of the orf protein has been hampered by the extremely low levels of expression observed in these mice, as estimated from the low levels of specific mrna. to study the properties of the orf protein, we attempted its expression in different cell types in cultur ... | 1992 | 1318937 |
| mls-1 is encoded by the long terminal repeat open reading frame of the mouse mammary tumor provirus mtv-7. | the murine mls-1 antigen is the prototype of endogenous superantigens, molecules whose activities lead to deletion of t cells expressing certain t-cell receptor v beta genes from the mature repertoire. however, mls-1 also stimulates t cells expressing these particular v beta genes (v beta 6, v beta 7, v beta 8.1, and v beta 9) in vitro, making it one of the strongest known t-cell activators. we have recently reported that the mls-1 gene is closely linked to the endogenous mammary tumor virus mtv ... | 1992 | 1319061 |
| tcrb-v3+ t-cell deletion and a new mouse mammary tumor provirus, mtv-44. | genes encoding endogenous superantigens causing tcrb-v3+ t-cell deletion co-segregate with mouse mammary tumor proviruses (mtv), mtv-3, mtv-6, and mtv-13. in addition mtv-1 has been implicated in deletion of these t cells. we have examined levels of tcrb-v3+ t cells and mtv integrations in the following offspring and their parental strains, [(cba-t6 x nzw)f1 x cba], [(cba x c3h/he)f1 x cba], and [(b10.s (9r) x nod]f1 mice. we show that a new mtv (mtv-44) from nzw mice and mtv-1 from c3h/he mice ... | 1992 | 1319398 |
| an activation-dependent, t-lymphocyte-specific transcriptional activator in the mouse mammary tumor virus env gene. | transcription of the complete mouse mammary tumor virus (mmtv) proviral genome in mouse cells is controlled by a strong promoter in its long terminal repeat. in the mouse t lymphoma el4, there is a second, activation-dependent transcriptional initiation site within the envelope (env) gene, from which a short mrna is generated, encoding the open reading frame of the long terminal repeat. we now report the isolation of a segment of the mmtv env gene (called meta, for mmtv env transcriptional activ ... | 1992 | 1320198 |
| suppression by a pine cone extract of pinus parviflora sieb et zucc of mammary tumour virus in milk of mice. | the intravenous or the oral administration of a pine cone extract of pinus parviflora sieb et zucc (fr vi) and the related synthetic agent (dhp-fa) to lactating shn mice prevented an increase of milk levels of mouse mammary tumour virus (mmtv) from day 7 to day 14 of lactation. furthermore, fr vi decreased the mmtv level at the 2nd lactation compared to the 1st lactation. this is the first report on the inhibition of milk mmtv of mice in the in vivo system. | 1992 | 1320357 |
| decreasing expression of nm23 gene in metastatic murine mammary tumors of viral etiology (mmtv). | murine mammary tumors induced by the murine mammary tumor virus (mmtv) were chosen to study the expression of the nm23 gene during the metastatic process because of their viral etiology, different from that of the previously reported experimental tumor systems. nm23 mrna levels are higher in non metastatic tumors than in metastatic ones. moreover, the nm23 expression is higher in tumors induced by the c3h variant of the mmtv than in tumors induced by the riii variant. these data are a further su ... | 1992 | 1320361 |
| mouse mammary tumor viruses express genes encoding a number of t cell superantigens. | | 1992 | 1320644 |
| retinoic acid activation and thyroid hormone repression of the human alcohol dehydrogenase gene adh3. | mammalian alcohol dehydrogenase (adh) catalyzes the oxidation of retinol to retinaldehyde, the rate-limiting step in the synthesis of retinoic acid. there exists a family of adh isozymes encoded by unique genes, and it is unclear which isozymes are most important for regulation of retinoic acid synthesis during differentiation or development. a region in the human adh3 promoter from -328 to -272 base pairs was shown previously to function as a retinoic acid response element (rare), prompting an ... | 1992 | 1321136 |
| mouse mammary tumor virus gene expression is suppressed by oligomeric ellagitannins, novel inhibitors of poly(adp-ribose) glycohydrolase. | oligomeric ellagitannins (nobotanins b, e, and k) were found to be potent inhibitors of poly(adp-ribose) glycohydrolase purified from mouse mammary tumor 34i cells. kinetic analysis revealed that the inhibition of nobotanin b (dimer) was competitive with respect to the substrate poly(adp-ribose), whereas nobotanin e (trimer) and nobotanin k (tetramer) exhibited mixed-type inhibition. these results suggest that the dimeric structure of ellagitannin may have a functional domain that competes with ... | 1992 | 1321148 |
| a viral long terminal repeat expressed in cd4+cd8+ precursors is downregulated in mature peripheral cd4-cd8+ or cd4+cd8- t cells. | the long terminal repeat from a thymotropic mouse mammary tumor virus variant, dmba-lv, was used to drive the expression of two reporter genes, murine c-myc and human cd4, in transgenic mice. expression was observed specifically in thymic immature cells. expression of c-myc in these cells induced oligoclonal cd4+ cd8+ t-cell thymomas. expression of human cd4 was restricted to thymic progenitor cd4- cd8- and cd4+ cd8+ t cells and was shut off in mature cd4+ cd8- and cd4- cd8+ t cells, known to be ... | 1992 | 1321339 |
| amplification of p450c21 expression in cultured mammalian cells. | we describe in this paper an investigation of mammalian expression systems for p450c21 (21-hydroxylase). four different promoters, the sv40 early and late promoters, mmtv-ltr, and cmv immediate early promoter were tested for their ability to drive the expression of p450c21 in cultured cos-1 cells. with the exception of mmtv-ltr, all drove the expression of similar levels of functional 21-hydroxylase. in addition, the rat-1 cell line was tested and shown to be suitable for the stable expression o ... | 1992 | 1321611 |
| effects of amphetamine on the development of mtv-induced mammary tumors in female mice. | female c3h/he mice carrying the mammary tumor virus (mtv) were monitored for mammary tumor incidence and latent periods while submitted to a daily subcutaneous injection with amphetamine (0,4 mg/kg/day). results show that amphetamine caused an increase in incidence and a decrease in latency of tumors compared with placebo. there was also appreciated a correlation with the lethality of mice. | 1992 | 1321936 |
| early and multifocal tumors in breast, salivary, harderian and epididymal tissues developed in mmty-neu transgenic mice. | transgenic mice carrying various oncogenes driven by mammary gland specific enhancers develop mammary tumors usually arising in a stochastic way. the only exception is a mouse lineage (tg.nf) carrying an activated rat neu oncogene driven by the murine mammary tumor virus long terminal repeat (mmtv-ltr) that gave rise to rapid and multifocal mammary tumors interpreted as a result of a single-step neoplastic transformation. the effect of the oncogene appeared to be specific for breast tissue, sinc ... | 1992 | 1322235 |
| positive and negative selection of tcrb-v6+ t cells. | tcrb-v6+ t cells are deleted by an endogenous superantigen probably encoded by a mouse mammary tumor provirus (mtv), mtv-7, in association with major histocompatibility complex (mhc) class ii molecules. in contrast, tcrb-v6+cd4+ t cells are positively selected by mhc class ii e molecules in mtv-7- mice. we have examined the levels of tcrb-v6+cd4+ and tcrb-v6+cd8+ t cells from six combinations of backcross mice. in this paper we show that: 1) tcrb-v6+cd8+ t cells can be positively selected by mhc ... | 1992 | 1322363 |
| interferon-alpha/beta in virus-induced mouse mammary carcinogenesis: effects on the spontaneous process and on the progression of transplanted pre-neoplastic lesions. | low levels of anti-viral activity, mainly interferon alpha/beta (ifn-alpha/beta), are regularly found in lymphoid tissues of balb/c mice infected with the c3h strain of mammary tumor virus. at the time of tumor development, significant amounts of anti-viral activity were detected in homogenates of spleen and mammary tumors, but not in blood and normal mammary glands. this activity is ph2-resistant and neutralized by antibody to ifn/alpha-beta. the pathogenetic role of ifn in mammary carcinogenes ... | 1992 | 1322380 |
| tcrb-v3+ t-cell deletion and a mouse mammary tumor provirus, mtv-27. | genes encoding superantigens which delete tcrb-v3+ t cells co-segregate with mouse mammary tumor proviruses (mtv), mtv-1, mtv-3, mtv-6, mtv-13, and mtv-44. we have examined percentages of tcrb-v3+ t cells and mtv integrations in [(b10 x nzb)f1 x b10.br] mice, and show that mtv-27 as well as mtv-3 from nzb mice co-segregate with genes encoding deletion ligands for tcrb-v3+ t cells without recombination. | 1992 | 1322864 |
| genetic analysis of the effects of mtv-2 on the t cell repertoire in the wxg-2 mouse strain. | in this report, the t cell repertoire was studied in a natural genetic model system using a novel mouse strain (wxg-2) carrying a single pathogenic mouse mammary tumor virus (mmtv) provirus (mtv-2) on an otherwise mmtv-free genetic background. the mtv-2 provirus has complete biological activity, produces infectious milk-transmitted virus, and contributes to mammary carcinogenesis by an insertion mutation mechanism. in mice carrying the mtv-2 provirus, t cells expressing v beta 14 were specifical ... | 1992 | 1323327 |
| expression of the mls-1a superantigen results in an increased frequency of v beta 14+ t cells. | minor lymphocyte-stimulating (mls) ag are alloantigens that stimulate t cells expressing specific v beta regions. recent studies have established that mls ag are examples of endogenous superantigens encoded by the products of endogenous mouse mammary tumor virus (mlv) genomes. in a mouse strain that expresses a given mammary tumor virus (mls) ag, reactive t cells expressing the corresponding v beta region are profoundly deficient, due at least in part to clonal deletion of the cells during their ... | 1992 | 1323609 |
| wild-type p53 is a cell cycle checkpoint determinant following irradiation. | cell cycle checkpoints appear to contribute to an increase in cell survival and a decrease in abnormal heritable genetic changes following exposure to dna damaging agents. though several radiation-sensitive yeast mutants have been identified, little is known about the genes that control these responses in mammalian cells. recent studies from our laboratory have demonstrated a close correlation between expression of wild-type p53 genes in human hematopoietic cells and their ability to arrest in g ... | 1992 | 1323840 |
| the pathobiology of salivary gland. ii. morphological evaluation of acinic cell carcinomas in the parotid gland of male transgenic (mmtv/v-ha-ras) mice as a model for human tumours. | in the transgenic tg.sh (mouse mammary tumour virus/v-ha-ras) mouse, designed to develop mammary tumours, occasional spontaneous salivary gland tumours have been reported, predominantly in males. the incidence and histomorphology of salivary gland tumours in 73 tg.sh mice were surveyed and in total, 21.9% developed both overt and microscopic parotid tumours. the majority developed between 73 and 150 days of age. in 31.5% of the tg.sh mice, occasional unilateral, but more frequently bilateral exo ... | 1992 | 1325087 |
| expression of gene-specific rna in cultured cells exposed to rotating 60-hz magnetic fields. | replicate sets of cultures of mouse and of human cells were exposed to cyclic, sine wave, 60-hz rotating magnetic fields of 1.0 gs (1 gs [symbol: see text] 0.1 mt) for 24-, 48-, or 72-h periods. total rna extracted from unexposed control and from magnetic field exposed cells was dot blot hybridized to a number of oncogene probes (including v-myc, v-fos, v-raf, and v-ha-ras), a probe for 3611 murine sarcoma virus, a probe for the 70,000 dalton heat shock protein (hsp70), and a probe for the long ... | 1992 | 1325160 |
| polyclonal and monoclonal antibodies monospecific to mmtv ltr orf protein produced in e. coli. | monoclonal and polyclonal antibodies specific to an open reading frame of the mouse mammary tumor virus long terminal repeat were generated using an open reading frame-beta-galactosidase fusion protein produced in e. coli. both antibodies reacted with the open reading frame-beta-galactosidase fusion protein but not with beta-galactosidase alone using an immunoblotting technique. it is concluded that these antibodies were specific for the protein encoded by the open reading frame of the mouse mam ... | 1992 | 1325284 |
| isolation and fractionation of retroviral trnas. | previous studies concerning the analysis of retroviral trna populations involved intracellular metabolic labeling of rna, followed by the isolation of viral rna and lengthy sucrose gradient centrifugation for the separation of trnas found in various viral compartments. a more rapid, convenient, and safer method for achieving similar aims is described. isolated total viral rna is end-labeled in vitro, and trna subgroups are fractionated using commercial nucleobond ax-20 mini columns. 2-d page ana ... | 1992 | 1325471 |
| superantigens. playing upon both sides. | | 1992 | 1326081 |
| stable transfection of androgen receptor and mmtv-cat into mammalian cells: inhibition of cat expression by anti-androgens. | a hormone-inducible transcriptional system has been established, based on the stable transfection of the rat androgen receptor (rar) and a reporter plasmid containing the mouse mammary tumour virus promoter linked to the chloramphenicol acetyltransferase gene (pmmtv-cat) into steroid receptor-negative cv-1 cells. first, the rar was stably introduced into cv-1 cells. single clones were tested for stable expression of functionally active ar by analysing the effect of dihydrotestosterone on inducti ... | 1992 | 1326316 |
| interplay of steroid hormone receptors and transcription factors on the mouse mammary tumor virus promoter. | the mouse mammary tumor virus (mmtv) promoter, that responds to glucocorticoids and progestins, contains a complex hormone response element (hre) in the long terminal repeat (ltr) region covered by a phased nucleosome. hormone treatment leads to alterations in chromatin structure that make the hre region more accessible to digestion by dnase i and permit binding of transcription factors, including nuclear factor i (nfi), immediately downstream of the hre. nfi acts as a basal transcription factor ... | 1992 | 1327070 |
| adoptive transfer of v beta 2-deleting activity with host cells from mice implanted with c4 preneoplastic hyperplastic alveolar nodules. | selective deletion of mature peripheral v beta 2+ t-cells was observed in balb/c mice implanted with the syngeneic c4 preneoplastic hyperplastic alveolar nodule (han) but not in mice with sham surgery (w. z. wei, r. ficsor-jacobs, s. j. tsai, and r. pauley, cancer res., 51:3331-3333, 1991). we now report the participation of host cells in that process. peripheral v beta 2+ t-cells were reduced by 50% or more 4 weeks after an i.v. injection of 10 x 10(6) spleen cells from c4 han-bearing mice. bot ... | 1992 | 1327503 |
| why is clonal deletion of neonatal thymocytes defective? | a major mechanism for establishing tolerance to some murine self antigens is clonal deletion of self reactive t cells in the thymus. this mechanism is responsible for the near absence of t cells displaying particular t cell receptor (tcr) v beta in strains of mice that express the major histocompatibility complex class ii e molecule and a protein encoded within the 3' open reading frame (orf) of certain endogenous mammary tumor viruses (mtv). however, clonal deletion does not operate in these sa ... | 1992 | 1327799 |
| mammalian expression vectors with modulatable promoters and two multiple cloning sites. | to facilitate the use of a wide range of selectable markers in transfection studies with human cells, in conjunction with the use of modulatable promoters for regulated expression of the genes of interest, we constructed two puc19-based mammalian expression vectors, each containing two lacz alpha-based multiple cloning sites (mcs). selectable markers can be inserted into the mcs derived from puc19, and the recombinants can be screened by lacz complementation. the genes of interest can be inserte ... | 1992 | 1327962 |
| [preliminary use of recombinant glycoprotein 52kd as an antigen in the diagnosis of human cytomegalovirus infection]. | interest in the human cytomegalovirus (hcmv) mainly derives from its associations with congenital malformations, mental retardation, and severe or fatal infections in immunosuppressed individuals such as transplant patients, tumor and aids patients. it is evidenced that there has been a need for a rapid and sensitive methods to detect an ongoing acute infection. the recent studies showed that high titers of antibody to the glycoprotein 52kd are present in sera of patients undergoing acute hcmv i ... | 1992 | 1328025 |
| a mammary cell-specific enhancer in mouse mammary tumor virus dna is composed of multiple regulatory elements including binding sites for ctf/nfi and a novel transcription factor, mammary cell-activating factor. | mouse mammary tumor virus (mmtv) is a milk-transmitted retrovirus involved in the neoplastic transformation of mouse mammary gland cells. the expression of this virus is regulated by mammary cell type-specific factors, steroid hormones, and polypeptide growth factors. sequences for mammary cell-specific expression are located in an enhancer element in the extreme 5' end of the long terminal repeat region of this virus. this enhancer, when cloned in front of the herpes simplex thymidine kinase pr ... | 1992 | 1328867 |
| overexpression of the n-ras proto-oncogene, not somatic mutational activation, associated with malignant tumors in transgenic mice. | we have produced transgenic mice that carry a foreign gene construct consisting of the n-ras proto-oncogene driven by the mouse mammary tumor virus (mmtv) long terminal repeat. overexpression of the normal n-ras gene is associated with development of hyperplasias and tumors in a variety of tissues. the tumors are clearly malignant, as evidenced by the presence of metastatic lesions. extensive analysis of the foreign ras gene in these tumors by use of polymerase chain reaction and sequencing demo ... | 1992 | 1328989 |
| retroviral superantigens. | | 1992 | 1329834 |