Publications

mutant and wild-type androgen receptors exhibit cross-talk on androgen-, glucocorticoid-, and progesterone-mediated transcription.	androgen, glucocorticoid, and progesterone receptors (ars, grs, and prs) often can regulate transcription via composite hormone response elements in target genes. we have used artificial and natural mutant ars from patients with androgen resistance to study their effects on dominant negative activity on wild type ar, gr, and pr function on mouse mammary tumor virus (mmtv) and tyrosine aminotransferase (tat) promoters. artificial ars that contained internal deletions within the amino-terminal reg ...	1997	9013763
rapamycin potentiates dexamethasone-induced apoptosis and inhibits jnk activity in lymphoblastoid cells.	the immunosuppressant rapamycin (rap) potentiated apoptosis of the murine t lymphoblastoid cell line s49 induced by dexamethasone (dex), while rap by itself did not induce apoptosis of the cells. fk506, in contrast, had no effect on dex-induced apoptosis; moreover, an excess of fk506 reversed the potentiation of apoptosis by rap, indicating that rap exerts its effects through binding to fkbp. both rap and fk506 enhanced the mmtv promoter activity by dexamethasone, suggesting that the potentiatio ...	1997	9016789
a novel tetracycline-dependent expression vector with low basal expression and potent regulatory properties in various mammalian cell lines.	the tetracycline-dependent expression system has gained increasing popularity for the expression of any gene of interest. careful choice of the expression vector has been suggested to exploit the full potential of this system. a novel tetracycline-sensitive expression vector based on a modified mouse mammary tumor virus promoter achieved considerably improved regulatory properties in a series of cell lines tested under transient and stable conditions. therefore, the applicability of the tetracyc ...	1997	9023121
androgen-dependent cell cycle arrest and apoptotic death in pc-3 prostatic cell cultures expressing a full-length human androgen receptor.	to assess the function of androgen receptor in androgen-independent prostate cancer cells, human pc-3 prostate carcinoma cells, which lack androgen receptor (ar) expression, were transfected with a full length human ar cdna sequence inserted into an episomal expression vector system. several clonal lines of transfected cells expressing varying levels of a 110 kda ar, as determined by immunoblotting and ligand binding assay, were isolated. the expressed ectopic receptors displayed nuclear binding ...	1997	9027364
sequence-specific dna binding and transcription factor phosphorylation by ku autoantigen/dna-dependent protein kinase. phosphorylation of ser-527 of the rat glucocorticoid receptor.	nre1 is a dna sequence element through which ku antigen/dna-dependent protein kinase (dna-pk) catalytic subunit represses the induction of mouse mammary tumor virus transcription by glucocorticoids. although ku is an avid binder of dna ends and has the ability to translocate along dna, we report that direct sequence-specific ku binding occurs with higher affinity (kd = 0.84 +/- 0.24 nm) than dna end binding. comparison of ku binding to several sequences over which ku can accumulate revealed two ...	1997	9038175
differential regulation of cell cycle characteristics and apoptosis in mmtv-myc and mmtv-ras mouse mammary tumors.	we have used the mmtv-myc and mmtv-ras transgenic mouse mammary tumor models (t. a. stewart et al., cell, 38: 627-637, 1984, and e. sinn et al., cell, 49: 465-475, 1987) to evaluate how the c-myc and v-ha-ras oncogenes influence tumor growth characteristics in vivo. mmtv-myc tumors had much higher levels of spontaneous apoptosis than mmtv-ras tumors, whereas intermediate levels were observed in mmtv-myc/ras tumors. significant differences in cell cycle characteristics were also observed in tumor ...	1997	9044833
paracrine transfer of mouse mammary tumor virus superantigen.	transfer of vsag7, the endogenous superantigen encoded in the mtv7 locus, from mhc class ii to mhc class ii+ cells has been suggested to occur both in vivo and in vitro. this transfer usually leads to the activation and deletion of t cells expressing responsive v beta s. however, there is no direct molecular evidence for such a transfer. we have developed an in vitro system which confirms this property of vsags. vsag7 was transfected into a class ii murine fibroblastic line. coculture of these c ...	1997	9053447
viral superantigen drives extrafollicular and follicular b cell differentiation leading to virus-specific antibody production.	mouse mammary tumor virus (mmtv[sw]) encodes a superantigen expressed by infected b cells. it evokes an antibody response specific for viral envelope protein, indicating selective activation of antigen-specific b cells. the response to mmtv(sw) in draining lymph nodes was compared with the response to haptenated chicken gamma globulin (np-cgg) using flow cytometry and immunohistology. t cell priming occurs in both responses, with t cells proliferating in association with interdigitating dendriti ...	1997	9053455
expression patterns of the four nuclear factor i genes during mouse embryogenesis indicate a potential role in development.	the nuclear factor i (nfi) family of site-specific dna-binding proteins is required for both the cell-type specific transcription of many viral and cellular genes and for the replication of adenovirus dna. although binding sites for nfi proteins within the promoters of several tissue-specific genes have been shown to be essential for their expression, it is unclear which nfi gene products function in specific tissues during development. we have isolated cdnas from all four murine nfi genes (gene ...	1997	9056636
generation of a tumorigenic milk-borne mouse mammary tumor virus by recombination between endogenous and exogenous viruses.	two novel exogenous mouse mammary tumor viruses (mmtv), balb2 and balb14, that encode superantigens (sags) with vbeta2+ and vbeta14+ specificities, respectively, were found in the balb/ct mouse strain. balb/ct females were crossed with akr/j males to generate f1 females. foster nursing of balb/ct mice on (balb/ct x akr/j)f1 mothers resulted in the generation of a new mouse strain, balb/cla, that had acquired a new exogenous mmtv (hereafter called la) with a vbeta6+/vbeta8.1+-t-cell-specific sag. ...	1997	9094666
an mmtv integration site maps near the distal end of mouse chromosome 11.		1997	9096121
nucleosome-mediated synergism between transcription factors on the mouse mammary tumor virus promoter.	in unstimulated mammalian cells and in saccharomyces cerevisiae, the mouse mammary tumor virus (mmtv) promoter is silent and organized into positioned nucleosomes, one of which encompasses the binding sites for glucocorticoid receptor (gr) and nuclear factor i (nfi). glucocorticoid induction in vivo involves a functional synergism between gr and nfi and simultaneous occupancy of the promoter sites for both proteins that cannot be reproduced on naked dna. the role of chromatin in the process of i ...	1997	9096316
ectopic expression of a-myb in transgenic mice causes follicular hyperplasia and enhanced b lymphocyte proliferation.	the a-myb gene is a transcription factor that shares structural and functional similarities with the v-myb oncogene. to date, v-myb is the only myb gene directly implicated in tumorigenesis, a property attributed to its transactivating ability. recent studies have demonstrated that a-myb, like v-myb, is a potent transcriptional activator, raising the possibility that a-myb may also participate in oncogenesis. to test this hypothesis, we generated fusion constructs that contained the human a-myb ...	1997	9096377
male infertility caused by epididymal dysfunction in transgenic mice expressing a dominant negative mutation of retinoic acid receptor alpha 1.	retinoids are thought to be required for the normal development and maturation of a number of tissues, including most epithelia. the action of retinoids appears to be mediated through the binding to retinoic acid receptors (rars) in the nucleus. the activity of retinoic acid can be inhibited in cells carrying dominant negative mutations of rar alpha. we created transgenic mice expressing a dominant negative mutant of rar alpha driven by the murine mammary tumor virus promoter. expression of the ...	1997	9096882
localization of a negative glucocorticoid response element of the human corticotropin releasing hormone gene.	corticotropin releasing hormone (crh) plays a primary role in mediating suprapituitary activation of the hypothalamic-pituitary-adrenal axis and is an important physiologic target of negative feedback regulation by glucocorticoids. we sought to define cis-acting regions of the crh promoter responsible for camp-dependent activation and glucocorticoid-dependent repression of crh promoter activity. in transiently transfected att-20 cells, camp-dependent transcriptional activation was mediated large ...	1997	9099914
transcription of human endogenous retroviral sequences related to mouse mammary tumor virus in human breast and placenta: similar pattern in most malignant and nonmalignant breast tissues.	the human genome contains a large variety of sequences related to the mouse mammary tumor virus (mmtv). we have investigated the range of expression of human endogenous retroviral sequences (hervs) related to mmtv (human mmtv-like; hml) as rna in 60 breast cancers, 8 nonmalignant breast tissues, and 9 placentas. this was monitored using hml group-specific oligonucleotide probes in hybridizations toward pcr amplificates of hml pol sequences and internal control. the degree of expression of five h ...	1997	9100993
a mutant rna pseudoknot that promotes ribosomal frameshifting in mouse mammary tumor virus.	a single a-->g mutation that changes a potential a.u base pair to a g.u pair at the junction of the stems and loops of a non-frameshifting pseudoknot dramatically increases its frameshifting efficiency in mouse mammary tumor virus. the structure of the non-frameshifting pseudoknot apk has been found to be very different from that of pseudoknots that cause efficient frameshifting [kang,h., hines,j.v. and tinoco,i. (1995) j. mol. biol. , 259, 135-147]. the 3-dimensional structure of the mutant pse ...	1997	9115361
a novel human wnt gene, wnt10b, maps to 12q13 and is expressed in human breast carcinomas.	several members of the wnt gene family have been shown to cause mammary tumors in mouse. using degenerate primer polymerase chain reaction (pcr) on human genomic dna, and specific pcr of cdna libraries, we have isolated a wnt gene which has not previously been described in human. the gene is the human homologue of mouse wnt10b, recently shown to be one of the oncogenes cooperating with fgf3 in the development of mouse mammary tumour virus (mmtv) induced mouse mammary carcinomas. the human wnt10b ...	1997	9121776
mouse mammary tumor virus superantigens require n-linked glycosylation for effective presentation to t cells.	mouse mammary tumor viruses (mmtvs) encode superantigens that associate with major histocompatibility complex class ii products on antigen-presenting cells and stimulate t cells in a v beta-specific manner. this t cell activation is critical for completion of the viral life cycle and vertical transmission to the next generation. to investigate the functional significance of extensive viral superantigen (sag) glycosylation, we disrupted the six potential sites for n-linked carbohydrate addition i ...	1997	9123822
how hormone receptor-dna binding affects nucleosomal dna: the role of symmetry.	molecular dynamics simulations have been employed to determine the optimal conformation of an estrogen receptor dna binding domain dimer bound to a consensus response element, ds(aggtcacagtgacct), and to a nonconsensus response element, ds(agaacacagtgacct). the structures simulated were derived from a crystallographic structure and solvated by a sphere (45-a radius) of explicit water and counterions. long-range electrostatic interactions were accounted for during 100-ps simulations by means of a ...	1997	9129808
t cell deletion induced by chronic infection with mouse mammary tumor virus spares a cd25-positive, il-10-producing t cell population with infectious capacity.	we found that t cells recognizing viral superantigen (vsag) can be subdivided into two distinct functional subsets based on il-2r alpha (cd25) expression. cd4+vbeta6+cd25- and cd4+vbeta6+cd25+ t cells were sensitive to vsag activation. when obtained from balb/c(sw) mice, both subsets were infected and capable to induce the tolerance process when transferred into noninfected recipients. however, in contrast to cd4+vbeta6+cd25- cells, which were gradually deleted in mmtv(sw)-infected mice, the poo ...	1997	9144476
an unlikely link? researchers probe viral role in breast cancer.		1997	9150180
the mouse mammary tumor associated gene int3 is a unique member of the notch gene family (notch4).	the int3 gene is frequently rearranged in mouse mammary tumor virus (mmtv)-induced mammary tumors of the czechii mouse strain. we have completed the nucleotide sequence of the normal 6.5 kb int3 rna and defined the intron/exon boundaries of the gene. the open reading frame of int3 rna should encode a 200 kd protein which shares 60% homology with the mouse homologue of drosophila notch. int3 is unique among other members of the notch family by containing 29 instead of 36 egf-like repeats in the e ...	1997	9150355
histone acetylation influences thyroid hormone and retinoic acid-mediated gene expression.	thyroid hormone (t3) and retinoic acid (ra) receptors regulate transcription of the rat growth hormone (gh) gene through binding to a common hormone response element (hre) in the promoter. we have investigated the effect of histone acetylation on hormone-dependent expression of the rat gh gene. we examined the effect of butyrate, which induces histone hyperacetylation, and trichostatin a (tsa), a highly specific inhibitor of histone deacetylases. gh-mrna levels were significantly increased in pi ...	1997	9150429
the nasal-associated lymphoid tissue of adult mice acts as an entry site for the mouse mammary tumor retrovirus.	mouse mammary tumor virus (mmtv) is a b type retrovirus transmitted to the suckling offspring through milk. mmtv crosses the intestinal barrier of neonates, initially infects the lymphoid cells of the peyer's patches, and later spreads to all lymphoid organs and to the mammary gland. adult mice can be infected systemically, but not by oral mmtv administration. in this study, we show that nasal administration of infected milk induces the infection of adult mice. nasal mmtv infection shared the ma ...	1997	9151713
genomic structures of viral agents in relation to the biosynthesis of selenoproteins.	the genomes of both bacteria and eukaryotic organisms are known to encode selenoproteins, using the uga codon for seleno-cysteine (sec), and a complex cotranslational mechanism for sec incorporation into polypeptide chains, involving rna stem-loop structures. these common features and similar codon usage strongly suggest that this is an ancient evolutionary development. however, the possibility that some viruses might also encode selenoproteins remained unexplored until recently. based on an ana ...	1997	9152512
possibilities of a viral etiology for human breast cancer. a review.	previous studies related mouse mammary tumor virus (mmtv) to human breast cancer. however, the presence of human endogenous retroviruses (hers) confounded these results. we selected a 660-bp sequence of the mmtv env gene with low homology to her (or any other known gene) and searched for a sequence homologous to it, using the polymerase chain reaction (pcr). the 660-bp sequence was detected in 131 (39%) of 335 unselected breast cancers, in 2 (6.9%) of 29 fibroadenomas, and in 2 (1.65%) of 121 no ...	1997	9152517
neu/erbb2 cooperates with p53-172h during mammary tumorigenesis in transgenic mice.	thirty percent of human breast cancers have amplification of erbb2, often in conjunction with mutations in p53. the most common p53 mutation in human breast cancers is an arg-to-his mutation at codon 175, an allele that functions in a dominant oncogenic manner in tumorigenesis assays and is thus distinct from loss of p53. transgenic mice expressing mouse mammary tumor virus-driven neu transgene (mmtv-neu) develop clonal mammary tumors with a latency of 234 days, suggesting that other events are ...	1997	9154814
mouse mammary tumor virus and the immune system.		1997	9160112
differential activity of progesterone and glucocorticoid receptors on mouse mammary tumor virus templates differing in chromatin structure.	in vivo, transcription factors interact with promoters having complex nucleoprotein structures. the transiently expressed progesterone receptor (pr) efficiently activates a transfected mouse mammary tumor virus (mmtv) promoter but is a poor activator of the mmtv promoter when it acquires an ordered chromatin structure as an endogenous, replicating gene. we show that the deficiency in pr activity is not due to insufficient expression of either b or a isoforms or competition between the two types ...	1997	9162055
the mtv29 gene encoding endogenous lymphoma superantigen in sjl mice, mapped to proximal chromosome 6.		1997	9162105
analysis of chromatin structure in vivo.	a number of important nuclear processes including replication, recombination, repair, and transcription involve the interaction of soluble nuclear proteins with dna assembled as chromatin. recent progress in a number of experimental systems has focused attention on the influence chromatin structure may exert on gene regulation in eukaryotes. with the advent of new technologies for the analysis of chromatin structure in vivo, studies evaluating the influence of chromatin structure on gene transcr ...	1997	9169200
crosslinking of progesterone receptor to dna using tuneable nanosecond, picosecond and femtosecond uv laser pulses.	uv laser crosslinking is a potentially powerful tool to investigate transient dna-protein interactions and binding kinetics in intact cells. as the processes underlying uv laser crosslinking are not fully understood, we have performed a study of the influence of laser pulses with different physical parameters on crosslinking of the progesterone receptor to an oligonucleotide containing a hormone-responsive element. we also studied the influence of the various parameters on the amount of laser-ir ...	1997	9171102
glucocorticoid receptor function possibly modulates cell-cell interactions in osteoblastic metastases on rat skeleton.	we analysed the glucocorticoid receptor (gr) function and its ability to modulate cell-cell interactions between the pa-iii rat prostate cancer and umr 106 osteoblast-like rat osteosarcoma cells as an in vitro model for studying gr function in pa-iii cell-induced tumor and blastic reaction in rat bone. intact gr was detected by ligand binding assays, dna band-shift, and gr trans-activation analysis of pa-iii and umr 106 cells transiently transfected with the mouse mammary tumor virus thymidine k ...	1997	9174122
second messengers induced by the envelope protein of a retrovirus.	the envelope protein (gp52) of the mouse mammary tumor virus (mmtv) can stimulate rna synthesis via binding to its cellular receptor on mammary epithelium. this effect was mimicked by either nitric oxide (no) or 8-bromo-cgmp and was blocked by an no inhibitor. furthermore, the effects of gp52 and 8-bromo-cgmp were not additive at maximal concentrations, suggesting that they were using the same signaling route. finally, gp52 elevated cgmp levels in mammary epithelium. these data suggest that gp52 ...	1997	9175626
long-term feeding of field bean protein containing protease inhibitors suppresses virus-induced mammary tumors in mice.	protease inhibitors (pis) of synthetic, bacterial or soybean origin have been shown to suppress carcinogen or radiation-induced rat mammary carcinogenesis. we report, for the first time, the effect of year-long feeding of field bean meal, a rich source of pis with a 24% protein content, at different protein levels in the diet, on mouse mammary tumor virus (mmtv)-induced mammary tumorigenesis in c3h/jax mice. weanling female mice were randomized and divided into groups and fed chow or chow with 2 ...	1997	9177450
effects of melatonin on mammary gland lesions in transgenic mice overexpressing n-ras proto-oncogene.	the oncostatic effects of melatonin on the mammary gland have been studied in transgenic mice carrying the n-ras proto-oncogene under the control of the mmtv-ltr. female (4-week-old) virgin mice with positive transgenic pedigrees were injected with melatonin (200 micrograms/mouse/ day, five times a week) or vehicle late in the evening. after 5 months of treatment, animals were sacrificed and the mammary glands were dissected for whole mounts, histology, and immunohistochemical analysis with a mo ...	1997	9181520
b cell response and histology of a retroviral infection in vivo.		1997	9186698
the ns1 protein of the autonomous parvovirus minute virus of mice blocks cellular dna replication: a consequence of lesions to the chromatin?	the nonstructural protein ns1 of the autonomous parvovirus minute virus of mice interferes with cell division and can cause cell death, depending on the cell transformation state. upon infection, the synthesis of ns1 protein is massively initiated during s phase. in this article, we show that minute virus of mice-infected cells accumulate in this phase. to investigate the link between ns1 accumulation and s-phase arrest, we have used stably transfected cells in which ns1 expression is under the ...	1997	9188601
proto-oncogene of int-3, a mouse notch homologue, is expressed in endothelial cells during early embryogenesis.	notch and its homologues are key regulatory receptors of the cell fate decision in various developmental processes. the int-3 oncogene was originally identified as a frequent target in mouse mammary tumour virus (mmtv)-induced mammary tumours and has been regarded as a notch homologue, based on its similarity to the intracellular domain of notch. studies with int-3 transgenic mice have suggested that the int-3 transgene affects the differentiation capacity of stem cells and leads to neoplastic p ...	1997	9189758
transgenic monocyte chemoattractant protein-1 (mcp-1) in pancreatic islets produces monocyte-rich insulitis without diabetes: abrogation by a second transgene expressing systemic mcp-1.	monocyte chemoattractant protein-1 (mcp-1) is a cc chemokine that attracts monocytes and t lymphocytes in vitro; however, its in vivo functions are poorly understood. to address this question, we constructed transgenic mice expressing mcp-1 controlled by an insulin promoter. these mice developed a chronic insulitic infiltrate composed of f4/80+ monocytes with minor populations of cd4+, cd8+, and b220+ cells. despite persistent transgene expression, the insulitis never progressed, and blood gluco ...	1997	9200479
fibroblast growth factor receptor signalling has a role in lobuloalveolar development of the mammary gland.	we have used the mouse mammary tumor virus promoter to express two dominant negative (dn) fibroblast growth factor receptor (fgfr) isoforms in the mammary epithelium of transgenic mice. while expression of dn-fgfr1(iiic) showed no discernible phenotype, a similar kinase negative form of fgfr2(iiib) caused a marked impairment of lobuloalveolar development. the growth retardation was apparent by mid-pregnancy and persisted in the post-partum glands. despite the substantial underdevelopment of the ...	1997	9202386
prolactin, epidermal growth factor or transforming growth factor-alpha activate a mammary cell-specific enhancer in mouse mammary tumor virus-long terminal repeat.	mammary specific expression of elevated levels of mouse mammary tumor virus (mmtv) contributes to mammary carcinogenesis. mechanisms which regulate provirus expression have not been completely defined. using a mmtv-long repeat terminal (mmtv-lrt) directed chloramphenicol-acetyltransferase (cat) reporter gene system and a human breast cancer cell line t47d, we demonstrate that prolactin (prl), epidermal growth factor (egf), or transforming growth factor-alpha (tgf-alpha) act on a mammary cell-spe ...	1997	9202398
preferential activation of fgf8 by proviral insertion in mammary tumors of wnt1 transgenic mice.	mouse mammary tumor virus (mmtv) is an insertional mutagen that has been demonstrated to transcriptionally activate flanking cellular proto-oncogenes. previously we have used mmtv infection to accelerate mammary tumorigenesis in wnt1 transgenic mice in order to identify genes that cooperate with the wnt1 oncogene. initial investigations into the resulting tumor collection, screened primarily by southern analysis, showed that three fibroblast growth factor genes, fgf8, fgf3 and fgf4, sustain acti ...	1997	9205106
plasmodium yoelii: resistance to disease is linked to the mtv-7 locus in balb/c mice.	we have identified congenic mouse strains that differ dramatically in resistance to infection with the murine malaria parasite plasmodium yoelii 17x. after infection, balb/c mice develop severe anemia and a high degree of parasitemia which sometimes results in death. the mtv-7 congenic strain balb.d2.mlsa, however, develops only a mild degree of anemia and parasitemia. in this paper we describe the course of the disease and discuss the potential role of mtv-7 and linked loci in control of this i ...	1997	9207740
mouse mammary tumor virus: a virus that exploits the immune system.	mouse mammary tumor virus (mmtv) causes mammary carcinomas and t-cell tumors in mice. mmtv variants that induce t-cell tumors have a large deletion within the u3 region of the long terminal repeat (ltr) compared to mmtv strains that induce mammary tumors. we provide evidence here that t-cell tropic mmtv strains lack a redundant binding site for a cellular protein called nbp (negative regulatory element binding protein). the lack of nbp-binding sites in t-cell tropic mmtv strains presumably leads ...	1997	9209337
differential hormone-dependent transcriptional activation and -repression by naturally occurring human glucocorticoid receptor variants.	the molecular mechanisms underlying primary glucocorticoid resistance or hypersensitivity are not well understood. using transfected cos-1 cells as a model system, we studied gene regulation by naturally occurring mutants of the glucocorticoid receptor (gr) with single-point mutations in the regions encoding the ligand-binding domain or the n-terminal domain reflecting different phenotypic expression. we analyzed the capacity of these gr variants to regulate transcription from different promoter ...	1997	9212062
expression of transgenic carcinoembryonic antigen (cea) in tumor-prone mice: an animal model for cea-directed tumor immunotherapy.	carcinoembryonic antigen (cea) is a tumor marker for the most common forms of adenocarcinomas. we have previously described c57bl/6 mice transgenic for the complete human cea gene. compared with humans, these mice reveal a conserved spatiotemporal cea expression pattern. to establish animal models for cea-targeted tumor immunotherapy, we have crossed cea transgenic mice with mice that are genetically predisposed to tumor development. these immunocompetent animals should allow optimization of imm ...	1997	9212243
the hepatitis b virus x gene induces p53-mediated programmed cell death.	the human hepatitis b virus (hbv) protein px is a multifunctional regulatory protein that is known to affect both transcription and cell growth. here we describe induction of apoptosis in nih 3t3 polyclonal cell lines upon stimulation of px expression from a dexamethasone inducible mouse mammary tumor virus (mmtv)-x expression vector. the effect of long-term px expression on the cell survival of mouse fibroblasts was confirmed in colony generation assays. this effect is not shared either by the ...	1997	9223332
both t and b cells shed infectious mouse mammary tumor virus.	mouse mammary tumor virus (mmtv) infected both b and t tissue culture cells and primary b and t cells in vivo after milk-borne transmission of the virus. the infected tissue culture cells processed viral proteins, and both these and primary b and t cells shed virus when cultured in vitro. moreover, the infected b and t tissue culture cells transmitted virus to uninfected mammary gland cells in vitro. the level of infection of these different cell types in vivo was dependent on the strain of mous ...	1997	9223496
evidence for immune facilitation of breast cancer growth and for the immune promotion of oncogenesis in breast cancer.	autoimmune diseases have been extensively studied in man and experimental animal models and salient points are reviewed, as a clear understanding of the immune mechanisms involved is essential if one is to understand the potential of immune interactions with established cancer cells or in the premalignant period of hyperplasia. such reactions may be of benefit to the host, with down regulation of tumor growth, or unfavourable, with facilitation of oncogenesis and cancer growth. in particular, ev ...	1996	9224971
mouse mammary tumor virus and mammary tumorigenesis in wild mice.	the current knowledge of the distribution of the mouse mammary tumor virus (mmtv) proviral genomes and the mechanism of mammary tumorigenesis by mmtv in mice, with the main emphasis on asian feral mice, is reviewed. the relevant earlier discoveries on the mode of mmtv transmission are summarized to provide an outline of the biology of mmtv. finally, the viral etiology of human breast cancer will be discussed.	1996	9110343
protein kinase c pathway potentiates androgen-mediated gene expression of the mouse vas deferens specific aldose reductase-like protein (mvdp).	transcription of the mouse vas deferens protein (mvdp) gene, a member of the aldo-keto reductase superfamily, is stimulated by androgens via the androgen responsive element (are) located in the proximal promoter (-111 to -97). we investigated interaction between androgens and the protein kinase c (pkc) signalling pathway. transcriptional regulation was determined by analysis of chloramphenicol acetyltransferase (cat). t47d cells were transiently transfected with 5' flanking mvdp dna promoter seq ...	1996	9027327
glucocorticoid receptor lacking the tau 1 transactivation domain is a gene-specific regulator of the wild-type glucocorticoid-receptor activity.	the glucocorticoid receptor (gr) contains a major transactivation function (tau 1), located in the n-terminal domain. tau 1 contributes to about 80% of the ligand-inducible transcriptional activity of gr. in this study, we show that gr devoid of tau 1 (symbol: see text] gr) can inhibit activation of gene expression by wild-type gr but this does not occur for all target genes. activation of the mouse mammary tumor virus promoter by wild-type gr in transiently transfected chinese hamster ovary (ch ...	1996	9022717
in vivo generation of 3' and 5' truncated species in the process of c-myc mrna decay.	it has been demonstrated that the half-life of c-myc mrna is modulated in response to physiological agents. the elucidation of the decay process and the identification of the critical steps in the in vivo c-myc mrna degradation pathway can be approached by following the fate of c-myc mrna under the influence of such factors. ifn-alpha was the factor used to modulate c-myc mrna half-life in hela 1c5 cells, a stable clone derived from hela cells. this cell line carries multiple copies of the c-myc ...	1996	9016668
recombinant fusion peptides containing single or multiple repeats of a ubiquitous t-helper epitope are highly immunogenic.	two recombinant mouse mammary tumor virus (mmtv) subunit vaccines have been constructed, in which linear sequences of the envelope gp 52 glycoprotein (ep3) or the superantigen (sag) have been fused to single or multiple repeats of a t-cell epitope (p30) from tetanus toxin. histidine tags or glutathione-s-transferase (gst) sequences have been included in the recombinant peptides in order to facilitate their purification by affinity chromatography. the ep3 or sag recombinant polypeptides with four ...	1996	9010240
estrogen induction of tgf-alpha is mediated by an estrogen response element composed of two imperfect palindromes.	to investigate the molecular mechanisms underlying the two- to three-fold induction of human transforming growth factor-alpha (htgf-alpha) mrna and two- to five-fold induction of htgf-alpha protein observed following estrogen treatment of hormone-responsive human breast cancer cell lines, the htgf-alpha promoter was assayed for ere-like sequences able to mediate estrogen induction of a heterologous gene. transient co-transfection of a chloramphenicol acetyl transferase (cat) construct consisting ...	1996	9010318
the dutpases from herpes simplex virus type 1 and mouse mammary tumour virus are less specific than the escherichia coli enzyme.	the enzyme dutpase catalyses the hydrolysis of dutp to dump and pyrophosphate, thereby suppressing incorporation of uracil into dna and providing a pool of dump, the precursor of dttp. hydrolysis of other nucleotides similar in structure to dutp would conceivably be physiologically detrimental and high specificity of the reaction seems to be necessary. in this work, we characterize the substrate specificity of the dutpases from herpes simplex virus type 1 (hsv-1) and mouse mammary tumour virus ( ...	1996	9000104
keratinocyte growth factor induces mammary and prostatic hyperplasia and mammary adenocarcinoma in transgenic mice.	the kinetics of solitary mammary tumor formation in transgenic mice bearing the mmtv-int-2 (fgf3) fusion gene suggest that several genetic events are required for tumorigenesis. in an effort to identify elements that could contribute to this oncogenic process, we used differential display pcr to identify gene products that are strongly and specifically induced in int-2 mammary tumors. using this approach we identified a member of the fgf family, kgf (fgf7), as a gene that is strongly upregulated ...	1996	9000125
isolation and identification of sex-specific cdna clones from the syrian hamster harderian gland.	syrian hamster harderian glands show a typical sexual dimorphism, with males having two secretory cell types and females having one cell type and intraluminal porphyrin accretions, among other differences. since these differences may be due to the expression of specific genes, our interest is to identify those genes and their role on the development and control of the sexual dimorphism. the experimental approach was to construct cdna libraries for male and female syrian hamster harderian glands ...	1996	8722704
transcriptional regulation by steroid hormones.	steroid hormones influence the transcription of a large number of genes by virtue of their interaction with intracellular receptors, which are modular proteins composed of a ligand binding domain, a dna binding domain, and several transactivation functions distributed along the molecule. the dna binding domain is organized around two zinc ions and allows the receptors to bind as homodimers to palindromic dna sequences, the hormones responsive elements (hre), is such a way that each homodimer con ...	1996	8733009
differential expression of human endogenous retroviral sequences similar to mouse mammary tumor virus in normal peripheral blood mononuclear cells.	mouse mammary tumor virus (mmtv) is a retrovirus that causes breast cancer in certain strains of mice. in a previous study we identified, by sequencing clones from human lymphocytes, six groups with similarities to mmtv. using a primer pair derived from pol sequences conserved within types a, b, and d retroviruses and probes from the six human mmtv-like (hml-1 to hml-6) groups in an internally controlled hybridization assay we investigated the normal variation of expression in pbmcs. variations ...	1996	8738436
mmtv-induced mutations in mouse mammary tumors: their potential relevance to human breast cancer.	in mouse mammary tumor virus (mmtv) infected mice, three identifiable stages of mammary tumorigenesis can be biologically defined: preneoplastic hyperplastic nodules, malignant tumor, and distant metastatic lesions (primarily in the lung). mmtv is a biological carcinogen which induces somatic mutations as consequence of its integration into the host cellular genome. each stage of mammary tumorigenesis appears to result from the clonal outgrowth of cells containing additional integrated proviral ...	1996	8738604
chromatin structure of the mmtv promoter and its changes during hormonal induction.	1. the packaging of nuclear dna in chromatin determines the conversion of the genetic information into a defined phenotype by influencing the availability of dna sequences for interactions with regulatory proteins and transcription factors. 2. we have studied the influence of the first level of chromatin organization, the nucleosome, on the activity of the mouse mammary tumor virus (mmtv) promoter. the mmtv promoter is strongly transcribed in response to steroid hormones but is virtually silent ...	1996	8743962
nucleotide sequences of env and 3'ltrorf genes of endogenous mouse mammary tumor viruses encoding superantigen specific for tcrvbeta2.		1996	8753866
frequent provirus insertional mutagenesis of notch1 in thymomas of mmtvd/myc transgenic mice suggests a collaboration of c-myc and notch1 for oncogenesis.	the mmtvd/myc transgenic mice spontaneously develop oligoclonal cd4+cd8+ t-cell tumors. we used provirus insertional mutagenesis in these mice to identify putative collaborators of c-myc. we found that notch1 was mutated in a high proportion (52%) of these tumors. proviruses were inserted upstream of the exon coding for the transmembrane domain and in both transcriptional orientations. these mutations led to high expression of truncated notch1 rnas and proteins (86-110 kd). in addition, many not ...	1996	8756350
a characteristic bent conformation of rna pseudoknots promotes -1 frameshifting during translation of retroviral rna.	the structures of four different rna pseudoknots that provide one of the signals required for ribosomal frameshifting in mouse mammary tumor virus have been determined by nmr. the rna pseudoknots have similar sequences and assume similar secondary structures, but show significantly different frameshifting efficiencies. the three-dimensional structures of one frameshifting and one non-frameshifting rna pseudoknot had been determined previously by our group. here we determine the structures of two ...	1996	8759314
cloning, expression and chromosomal localization of wnt-13, a novel member of the wnt gene family.	the wnt genes, encoding structurally-related secreted glycoproteins, are implicated in mammary carcinogenesis induced by mouse mammary tumor virus. in search of the wnt gene(s) expressed in human gastric cancer, a wtgc1 cdna fragment sharing 66.9% amino-acid homology with human and mouse wnt-2 was isolated by degenerate polymerase chain reaction. the human gene corresponding to wtgc1 was designated as wnt-13 and overlapping wnt-13 cdnas were cloned. nucleotide sequence analysis indicated that th ...	1996	8761309
overexpression of int-5/aromatase in mammary glands of transgenic mice results in the induction of hyperplasia and nuclear abnormalities.	our recent studies have shown that the cellular gene at the mouse mammary tumor virus integration site in the int-5 locus is aromatase. to study the role of int-5/aromatase in normal mammary development and mammary neoplasia, we have generated transgenic mice that overexpress int-5/aromatase under the control of mouse mammary tumor virus enhancer/promoter. all the transgenic virgin (n = 10) and postlactational (n = 15) females that overexpress int-5/aromatase show various histological abnormalit ...	1996	8764102
glucocorticoid receptor structure and function in glucocorticoid-resistant small cell lung carcinoma cells.	human small cell lung carcinomas (sclcs) frequently express the adrenocorticotrophin precursor gene proopiomelanocortin. glucocorticoids usually fail to inhibit this ectopic adrenocorticotrophin production, in contrast to their effects in the pituitary. we have shown three human sclc cell lines to be globally resistant to glucocorticoid action; in two of these lines this occurs despite the presence of glucocorticoid receptors (gr+). accordingly, we have cloned and sequenced the gr coding region ...	1996	8764121
cd28/ctla4-b7 interaction is dispensable for t cell stimulation by mouse mammary tumor virus superantigen but not for b cell differentiation and virus dissemination.	b cells are the primary targets of infection for mouse mammary tumor virus (mmtv). however, for productive retroviral infection, t cell stimulation through the virally-encoded superantigen (sag) is necessary. it activates b cells and leads to cell division and differentiation. to characterize the role of b cell differentiation for the mmtv life cycle, we studied the course of infection in transgenic mice deficient for cd28/ctla4-b7 interactions (mctla4-h gamma 1 transgenic mice). b cell infectio ...	1996	8766566
fish glucocorticoid receptor with splicing variants in the dna binding domain.	here we describe the isolation of a rainbow trout cdna containing an entire gr coding region. although the encoded protein is highly homologous to other grs, especially in its dna binding domain, it contains a nine amino acid insertion between the two zinc fingers. this novel form is found in all rainbow trout tissues examined; however, the testis also contains a splice variant lacking this insert, making it completely continuous to other grs. in transient transfection assays of cultured cells, ...	1996	8766708
a novel endogenous mouse mammary tumor virus locus in asian wild mice and its evolutionary divergency.	the divergency of endogenous mouse mammary tumor virus (mmtv) in european mouse strains indicates acquisition of exogenous mmtv into their genomes during evolution. in the present study, we selected two strains of asian wild mice, cas-hmi (mus musculus castaneus) and sub-kjr (m. m. subspecies) to investigate a possible divergency of endogenous mmtvs among asian mouse strains. southern blot analysis and polymerase chain reaction (pcr) demonstrated that cas-hmi and sub-kjr have the full structure ...	1996	8766928
variable expression of human transgenes in shn mice.	the mouse mammary tumour virus/human transforming growth factor alpha (mmtv/htgf alpha) gene or the mouse whey acidic protein/human growth hormone (mwap/hgh) gene was introduced to a high mammary tumour strain of shn virgin females by mating with males bearing each gene. we maintained transgenic mice by backcrossing males with the htgf alpha transgene or high serum hgh levels (> 50 ng/ml) to shn virgins in the subsequent generations. expression of the transgenes was examined at each generation. ...	1996	8783173
loss of glucocorticoid-dependent growth inhibition in transformed mouse lung cells.	transformed a5 mouse lung cells were examined for mechanisms that may explain their loss of glucocorticoid-induced growth inhibition. these cells were compared to nontransformed c10 mouse lung cells, which retain this response. southern blot analysis revealed no major differences in the amount or pattern of restriction fragments for the glucocorticoid receptor (gr) gene between the responsive and nonresponsive cells. northern blot analysis demonstrated that both cell lines expressed gr mrna at s ...	1996	8784464
immune response to mouse mammary tumour virus.	superantigens of mouse mammary tumor virus induce a strong cognate interaction between t cells and b cells. in addition to amplifying the virus-infected b-cell pool, this superantigen-driven interaction leads to the differentiation of virus-specific b cells into plasma cells. successful interaction between t cells and b cells is required for completion of the viral life cycle.	1996	8794013
the neonatal fc receptor is not required for mucosal infection by mouse mammary tumor virus.	the milk-borne mouse mammary tumor virus (mmtv) infects newborn mice via the intestine. infection is initially restricted to peyer's patches and later spreads to the epithelial cells of the mammary gland. the receptor that mediates uptake and transport of mmtv across the intestinal barrier has not yet been identified, the neonatal fc receptor (nfcr), which is expressed by enterocytes during the first two weeks of life, is downregulated at weaning, and its disappearance correlates with the onset ...	1996	8794377
degradation of topoisomerase iialpha during adenovirus e1a-induced apoptosis is mediated by the activation of the ubiquitin proteolysis system.	the human epithermoid carcinoma-derived cell line ma1, established by introduction of the adenovirus e1a 12 s cdna linked to the mouse mammary tumor virus long terminal repeat, elicits apoptosis after induction of e1a12s in response to dexamethasone. the level of topoisomerase iialpha begins to decrease steeply within 36 h preceding the onset of dna fragmentation, whereas its mrna level is unchanged (nakajima, t., ohi, n., arai, t., nozaki, n., kikuchi, a., and oda, k. (1995) oncogene 10, 651-66 ...	1996	8798759
expression of a truncated int3 gene in developing secretory mammary epithelium specifically retards lobular differentiation resulting in tumorigenesis.	insertional mutation of the int3 gene, a member of the notch gene family, is frequently associated with primary mouse mammary tumors induced by the mouse mammary tumor virus (mmtv). a major consequence of these mutations is the production of a shortened 2.4-kb tumor specific int3 rna transcript that encodes the entire intracellular domain of the int3 protein. previous studies have demonstrated that mammary gland development and function was severely impaired in transgenic mice expressing the tru ...	1996	8620493
recipient polyclonal b cell activation and immunoglobulin production induced by priming with a retroviral superantigen.	the superantigen vsag-7 (or mis 1a) is a membrane glycoprotein encoded by the endogenous retrovirus mouse mammary tumor virus 7 (mmtv-7) and is highly stimulatory for v beta 6/cd4+ t cells. priming of adult mmtv-7-negative mice with vsag-7-expressing cells initially results in the activation of the peripheral v beta 6/cd4+ t cell compartment and is followed by t cell tolerance to the superantigen. during the course of tolerance induction the number of recipient b lymphocytes increases in the lym ...	1996	8620553
mouse mammary-tumor virus: the basics of an oncogenic retrovirus. steiner young investigator award lecture 1995.		1996	8621243
interactions of a transcriptional activator in the env gene of the mouse mammary tumor virus with activation-dependent, t cell-specific transacting factors.	the mouse mammary tumor virus env gene contains a transcriptional activator (meta) that can control transcription of the adjacent long terminal repeat region. transcriptional control by meta parallels that of several lymphokine genes, being specific to t cells, dependent on their activation, and inhibited by the immunosuppressive drug cyclosporine (csa). dnase i footprinting indicated that nuclear factors from activated t lymphocytes bound a promoter-proximal site, meta(p), and a promoter-distal ...	1996	8621538
ndf/heregulin induces persistence of terminal end buds and adenocarcinomas in the mammary glands of transgenic mice.	neu differentiation factor (ndf), a member of the neuregulin family of ligands of erbb receptors, induces both differentiative and mitogenic effects on cultured human mammary epithelial cells. since members of the epidermal growth factor receptor family, including neu/erbb2, have been implicated in mammary carcinoma, we wished to know whether a potential ligand of this family, ndf, could induce such effects in the mammary gland in vivo. we therefore targeted expression of ndf to the mammary glan ...	1996	8622899
purification and stabilization of transcriptionally active glucocorticoid receptor.	a major obstacle to the purification of glucocorticoid receptor (gr) is the very high nonspecific surface adsorption of this protein. this phenomenon is a property of the gr itself and does not reflect overall protein concentration or buffer conditions. we have observed that the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (chaps) is unique in its ability to stabilize the receptor and largely eliminate loss to nonspecific adsorption. we have coupled thi ...	1996	8626700
requirements for mouse mammary tumour virus internalization in mouse mammary epithelial cells.	methylamine, a lysosomotropic alkalinizing agent, blocked mouse mammary tumour virus (mmtv) infection in normal mouse mammary epithelium, suggesting that internalization and acidification are necessary for cell penetration. this mechanism was further supported by the fact that intact mmtv induced the translocation of its cellular binding protein from the plasmalemma to the microsomes; however, isolated gp52, the mmtv envelope protein that binds this receptor, did not redistribute the binding pro ...	1996	8627268
in vivo effects of a recombinant vaccinia virus expressing a mouse mammary tumor virus superantigen.	early after infection, the mouse mammary tumor virus (mmtv) expresses a superantigen (sag) at the surface of b lymphocytes. interaction with the t-cell receptor vbeta domain induces a polyclonal proliferative response of the sag-reactive t cells. stimulated t cells become anergic and are deleted from the t-cell repertoire. we have used a recombinant vaccinia virus encoding the mmtv(gr) sag to dissect the effects of the retroviral sag during an unrelated viral infection. subcutaneous infection wi ...	1996	8627779
suppression of translation frameshift by upstream termination codon.	retroviruses employ translation frameshift for gene expression. translation frameshift takes place at the slippery heptanucleotide sequence on mrna. a downstream stem-loop structure (and a pseudoknot formed by the stem-loop) enhances the level of ribosomal frameshifting. here, we describe that an upstream termination codon suppresses the ribosomal frameshifting, leading to reduction in the expression of downstream genes.	1996	8630007
activated neu induces rapid tumor progression.	expression of the activated neu oncogene in transgenic mice has been associated with both the synchronous (single-step) and the stochastic (multistep) transformation of the mammary epithelium. to determine the basis for these conflicting observations, additional strains of transgenic mice carrying the activated neu oncogene under the transcriptional control of the mouse mammary tumor virus promoter/enhancer were produced. activated neu transgene expression, as measured by in situ hybridization a ...	1996	8631805
multiple levels of mhc class i down-regulation by ras oncogenes.	a number of tumours and oncogene transformed cells displayed reduced mhc class i surface expression which seemed to enable their escape from immune surveillance. to test whether oncogenic activation is directly involved in suppressing mhc class i expression, a model of inducible oncogene expression was chosen. mouse fibroblasts transfected with different oncogenes expressed under the control of the dexamethasone-inducible mmtv promoter were analysed in the presence and absence of hormone for the ...	1996	8633212
sequence-specific dna binding by ku autoantigen and its effects on transcription.	dna-dependent protein kinase (dna-pk) has been implicated in several nuclear processes including transcription, dna replication, double-stranded dna break repair, and v(d)j recombination. linkage of kinase and substrate on dna in cis is required for efficient phosphorylation. recruitment of dna-pk to dna is by ku autoantigen, a dna-end-binding protein required for dna-pk catalytic activity. although ku is known to translocate along naked dna, how dna-end binding by ku might lead to dna-pk-mediat ...	1996	8637578
tissue-targeted antisense c-fos retroviral vector inhibits established breast cancer xenografts in nude mice.	the c-fos proto-oncogene has been implicated as a regulator of estrogen-mediated cell proliferation. we have tested the tissue specificity and antitumor efficacy of a mouse mammary tumor virus-regulated antisense c-fos retroviral vector. systemically administered vector could be detected in several tissues but was only expressed in breast epithelium, thus supporting targeting to mouse mammary tumor virus-regulated tissues. ex vivo transduction of 30-70% of mcf-7 human breast cancer cells produce ...	1996	8640767
lack of mmtv superantigen presentation in mhc class ii-deficient mice.	mammary tumor viruses (mmtvs) as well as their endogenous counterparts encode superantigens which react with t cells expressing particular t cell receptor v beta chains. several lines of evidence indicated that mhc class ii is required for the functional presentation of these superantigens. here we provide direct proof that the function of superantigens is abrogated in the absence of mhc class ii expression. no deletion of mls-1-reactive t cells was observed in mhc class ii-deficient mice, and s ...	1996	8640859
deletion of peripheral v beta 14+ t cells by mtv-2-encoded viral superantigen preceded by blastogenesis and dna synthesis but not by specific expansion.	exogenous and endogenous mouse mammary tumor viruses encode superantigen (sag) in the 3' long terminal repeat. we investigated the immune response of lymph node cells to the viral sag encoded by endogenous mtv-2 (vsag-2) by i.v. injecting splenocytes from mtv-2+ mice into mtv-2- congenic counterparts. vsag-2 stimulation induced blastogenesis and dna synthesis but not subsequent specific expansion of v beta 14+cd4+ or cd8+ t lymphocytes. instead, immediate deletion of these t cells progressed aft ...	1996	8640876
visualization of glucocorticoid receptor translocation and intranuclear organization in living cells with a green fluorescent protein chimera.	a highly fluorescent mutant form of the green fluorescent protein (gfp) has been fused to the rat glucocorticoid receptor (gr). when gfp-gr is expressed in living mouse cells, it is competent for normal transactivation of the gr-responsive mouse mammary tumor virus promoter. the unliganded gfp-gr resides in the cytoplasm and translocates to the nucleus in a hormone-dependent manner with ligand specificity similar to that of the native gr receptor. due to the resistance of the mutant gfp to photo ...	1996	8643491
grip1, a novel mouse protein that serves as a transcriptional coactivator in yeast for the hormone binding domains of steroid receptors.	the yeast two-hybrid system was used to isolate a clone from a 17-day-old mouse embryo cdna library that codes for a novel 812-aa long protein fragment, glucocorticoid receptor-interacting protein 1 (grip1), that can interact with the hormone binding domain (hbd) of the glucocorticoid receptor. in the yeast two-hybrid system and in vitro, grip1 interacted with the hbds of the glucocorticoid, estrogen, and androgen receptors in a hormone-regulated manner. when fused to the dna binding domain of a ...	1996	8643509
glucocorticoid and progestin receptors are differently involved in the cooperation with a structural element of the mouse mammary tumor virus promoter.	we have previously characterized a regulatory element located between -294 and -200 within the mouse mammary tumor virus (mmtv) long terminal repeat (ltr). this element termed aa element cooperates with the glucocorticoid response elements (gres) for glucocorticoid activation. here we show that in a mmtv ltr wild type context, the deletion of this element significantly reduces both glucocorticoid and progestin activation of the promoter. deletion of the two most distal gres forces the glucocorti ...	1996	8643531
effect of transfection of a drosophila topoisomerase ii gene into a human brain tumour cell line intrinsically resistant to etoposide.	the human brain tumour cell line hbt20 is intrinsically resistant to etoposide and does not express mdr-1 mrna. these studies were conducted to determine whether transfecting a drosophila (d) topoisomerase ii (topo ii) gene into hbt20 cells could increase their sensitivity to etoposide. a d-topo ii construct in a pmamneo vector under the control of a mouse mammary tumour virus (mmtv) promoter was transfected into hbt20 cells. the gene is inducible by dexamethasone (dex). the growth rate of the t ...	1996	8645582
the hormone responsive region of mouse mammary tumor virus positions a nucleosome and precludes access of nuclear factor i to the promoter.	the mouse mammary tumor virus (mmtv) promoter is transcriptionally silent prior to hormonal induction, partly because its organization into phased nucleosomes precludes access of transcription factors to their cognate sites. a t47d-derived cell line carrying a single integrated copy of the mmtv promoter exhibited a positioned nucleosome, which prevented binding of nuclear factor i (nfi). to study the molecular mechanisms controlling promoter accessibility we have made use of a strong chimeric tr ...	1996	8645614
quantitative flow cytometry reveals a hierarchy of glucocorticoid effect on cell surface mouse mammary tumor virus gp52.	a flow cytometry protocol with cm mouse mammary tumor cells (mm5mt/c1) was utilized to provide a fluorescence measurement of hormone-mediated changes in mouse mammary tumor virus (mmtv) cell surface envelope glycoprotein (gp52 csa). standards permitted gp52-specific fluorescence intensity to be measured as molecules of equivalent soluble fluorescein (mesf). the feasibility of using mesf determinations to reflect hormone-modulated changes in continuously infected cells was tested. a panel of five ...	1996	8645615
a v beta 4-specific superantigen encoded by a new exogenous mouse mammary tumor virus.	the superantigen (sag) expressed by mouse mammary tumor virus (mmtv) has been shown to play an essential role in the course of the viral life cycle. in the present study, we describe a v beta 4-specific sag encoded by a new exogenous mmtv carried by the sim mouse strain. this is the first report of a viral or bacterial sag reacting with mouse v beta 4+ t cells. injection of mmtv(sim) into adult balb/c mice leads to a rapid and strong stimulation of v beta 4+ cd4+ t cells, followed by a slow dele ...	1996	8647159