| interaction of steroid hormone receptors with transcription factors involves chromatin remodelling. | the mechanism by which steroid hormones modulate promoter utilization is not clear. evidence from transfection studies and cell-free assays points to an interaction of the hormone receptors with general transcription factors, as well as with sequence-specific transcription factors. moreover co-activators or transcription intermediary factors, have been identified which could mediate some of the transcriptional effects of the hormone-receptor complex. however, in addition to this interaction of r ... | 1996 | 8603047 |
| the role of superantigens in virus infection. | murine mammary tumor viruses are retroviruses which encode superantigens capable of stimulating t cells via superantigen-reactive t-cell receptor v beta chains. murine mammary tumor viruses are transmitted to the suckling offspring through the milk. we have established that b cell-deficient pups which were foster-nursed by virus-secreting mice do not transfer infectious murine mammary tumor viruses to their offspring. no murine mammary tumor virus proviruses could be detected in the spleen and m ... | 1995 | 8613488 |
| influence of hormone antagonists on chromatin remodeling and transcription factor binding to the mouse mammary tumor virus promoter in vivo. | steroid hormones act via a group of high affinity receptors that regulate transcription by binding to hormone response elements located in the promoters of hormone-inducible genes. our understanding of these processes has been greatly enhanced by the use of steroid hormone antagonists in both clinical and experimental procedures. however, despite their usefulness in these applications, much about their mechanisms of action remains to be elucidated. using in vivo analysis techniques, we investiga ... | 1995 | 8614418 |
| endogenous mouse mammary tumor virus mtv-17 is involved in mtv-2-induced tumorigenesis in gr mice. | mtv-2 is an endogenous mouse mammary tumor virus (mmtv) that is responsible for the induction of mammary gland tumors in the high mammary gland tumor-incidence strain gr. gr animals inherit four different endogenous mmtvs in addition to mtv-2: mtv-3, mtv-7, mtv-8 and mtv-17. in this study we analyzed the involvement of these nonpathogenic endogenous proviruses in the mammary gland tumors caused by mtv-2. we showed that mtv-17 is expressed in the mammary gland of gr mice, efficiently packaged int ... | 1996 | 8615016 |
| herpesvirus saimiri open reading frame 14, a protein encoded by t lymphotropic herpesvirus, binds to mhc class ii molecules and stimulates t cell proliferation. | herpesvirus saimiri (hvs) is an oncogenic, lymphotropic, gamma-herpesvirus that transforms human and simian t cells in vitro and causes lymphomas and leukemias in various species of new world primates. nucleotide sequence analysis of the hvs genome revealed an open reading frame with 22% amino acid identity to the mouse mammary tumor virus 7 superantigen. in this study, we demonstrate that this open reading frame, hvs14, encodes a heavily glycosylated protein that is secreted. both the hvs14 pre ... | 1996 | 8617948 |
| identification of a cytoplasmic, phorbol ester-inducible isoform of protein tyrosine phosphatase epsilon. | the protein-tyrosine phosphatase epsilon (ptp epsilon) is a transmembranal, receptor-type protein that possesses two phosphatase catalytic domains characteristic of transmembranal phosphatases. here we demonstrate the existence of a nontransmembranal isoform of ptp epsilon, ptp epsilon-cytoplasmic. ptp epsilon-cytoplasmic and the transmembranal isoform of ptp epsilon have separate, nonoverlapping expression patterns. further, the data clearly indicate that control of which of the two isoforms is ... | 1995 | 8618876 |
| 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 |
| induction of cytotoxic t lymphocytes to murine mammary tumor cells with a kd-restricted immunogenic peptide. | a synthetic peptide e474 sfavattal, derived from the sequence of mouse mammary tumor virus envelope protein, was previously shown to bind class i mhc kd. immunization of balb/c mice with e474 in 50% incomplete freund's adjuvant (ifa) followed by in vitro stimulation of immune cells with e474-coated antigen-presenting cells resulted in peptide-specific cytotoxic t lymphocytes (ctl). furthermore, anti-e474 ctl lysed mammary tumor cell lines d2f2 and d2a1, derived from a spontaneous tumor that aros ... | 1996 | 8647629 |
| function of directly repeated half-sites as response elements for steroid hormone receptors. | the mouse mammary tumor virus promoter has been shown to be inducible by glucocorticoids and progesterone. although steroid hormone receptors bind with high affinity to palindromic response elements, the hormone-responsive region of the mouse mammary tumor virus promoter contains a pair of directly repeated half-sites that are important for hormone inducibility. recent experiments have also indicated that direct repeats can function as estrogen response elements. here, we have investigated dna b ... | 1996 | 8647867 |
| in vivo t cell response to viral superantigen. selective migration rather than proliferation. | superantigens induce t cell activation and proliferation in vitro, and some also induce cell activation in vivo. mmtv(sw) is an infectious mouse mammary tumor virus (mmtv) encoding a superantigen with the same vbeta specificity as mis-1a (mtv-7), which induces a strong local response in vivo. injection of mmtv(sw) into mouse footpads leads to accumulation of superantigen-reactive t cells (vbeta6+cd4+) and b cells in the draining lymph nodes (ln). we investigated the kinetics of this cell accumul ... | 1996 | 8648102 |
| conformation of a non-frameshifting rna pseudoknot from mouse mammary tumor virus. | the solution conformation of an rna pseudoknot, which is a mutant of the pseudoknot required for ribosomal frameshifting in mouse mammary tumor virus, has been determined by nmr. the 32-nucleotide rna pseudoknot does not promote efficient frameshifting, although its sequence is very similar to the efficient frameshifting pseudoknot whose structure was recently determined by our group. 13c-labeling of the rna and 13c-edited nmr techniques were used to facilitate spectral assignment. the three-dim ... | 1996 | 8648641 |
| superantigens: structure and relevance to human disease. | superantigens are a class of immunostimulatory molecules produced by bacteria and viruses. their potent immune effects are due to their unique ability to bind to the major histocompatibility complex (mhc) outside the antigen-binding cleft and to stimulate t cells in a t-cell receptor (tcr) vbeta-specific manner. structural studies have revealed the binding sites involved in the mhc/superantigen/tcr complex. the bacterial superantigens are responsible for a number of syndromes, including food poi ... | 1996 | 8650257 |
| localization of mtv44 to the centromeric region of mouse chromosome 11. | | 1996 | 8661707 |
| development of cell lines capable of complementing e1, e4, and protein ix defective adenovirus type 5 mutants. | the cloning capacity of currently available e1- and e3-deleted adenovirus (ad) vectors does not exceed 8 kb. to increase capacity and improve vector safety further, we have explored the possibility that early region 4 (e4) and the gene encoding protein ix (pix) might also be deleted. to generate cell lines expressing sufficient levels of e4 and pix proteins in trans in addition to e1-encoded proteins to complement mutations in these genes, we transformed 293 cells with constructs containing the ... | 1995 | 8664382 |
| telomerase activation in mouse mammary tumors: lack of detectable telomere shortening and evidence for regulation of telomerase rna with cell proliferation. | activation of telomerase in human cancers is thought to be necessary to overcome the progressive loss of telomeric dna that accompanies proliferation of normal somatic cells. according to this model, telomerase provides a growth advantage to cells in which extensive terminal sequence loss threatens viability. to test these ideas, we have examined telomere dynamics and telomerase activation during mammary tumorigenesis in mice carrying a mouse mammary tumor virus long terminal repeat-driven wnt-1 ... | 1996 | 8668193 |
| gene expression in rainbow trout (oncorhynchus mykiss) following intramuscular injection of dna. | expression of the firefly luciferase gene under the control of viral or fish promoters was observed in fish tissue after direct dna injection of plasmid dna. plasmid dna containing the firefly luciferase gene was injected into the skeletal muscle of rainbow trout (oncorhynchus mykiss), and levels of luciferase activity were found to be dependent on the controlling promoter and the amount of injected dna. plasmids using the cytomegalovirus immediate early promoter (cmv-iep) consistently produced ... | 1996 | 8680523 |
| notch4/int-3, a mammary proto-oncogene, is an endothelial cell-specific mammalian notch gene. | the int-3 oncogene was identified as a frequent target in mouse mammary tumor virus (mmtv)-induced mammary carcinomas and encodes the intracellular domain of a novel mouse notch gene. to investigate the role of the int-3 proto-oncogene in mouse development and carcinogenesis, we isolated cdna clones corresponding to the entire coding potential of the int-3 proto-oncogene. we propose to name this gene notch4 and reserve the int-3 nomenclature for references to the oncogenic form. the deduced amin ... | 1996 | 8681805 |
| the mouse wnt-10b gene isolated from helper t cells is widely expressed and a possible oncogene in br6 mouse mammary tumorigenesis. | from libraries made from activated mouse t lymphocytes, we have isolated cdnas encoding wnt-10b, a new member of the wnt family of developmental control genes. this protein appears to be the mammalian orthologue of wnt-10b, first identified in several non-mammalian vertebrates and recently in mouse. the mrna expression pattern of mouse wnt-10b indicates that it is induced following activation of helper t cells, but is also expressed in a variety of other tissues and cells of fetal or adult origi ... | 1996 | 8682303 |
| the role of cd28 costimulation in immune-mediated responses against mouse mammary tumor viruses. | infectious mouse mammary tumor viruses (mmtv) encode superantigens (sag) which, when presented in association with permissive class ii mhc molecules, are recognized by those t cells that express appropriate tcrs. recent findings have indicated that expression of a permissive mhc class ii product and of a specific tcr are also critical to susceptibility of newborn mice to infection with milk-borne mmtv, suggesting that sag-mediated t cell activation may play a facilitating role in viral infection ... | 1996 | 8690899 |
| efficient and specific ribozyme-mediated reduction of bovine alpha-lactalbumin expression in double transgenic mice. | transgenic mice carrying a bovine alpha-lactalbumin (alpha-lac) specific ribozyme gene under the transcriptional control of the mouse mammary tumor virus long terminal repeat were generated and cross-bred with animals that highly express a bovine alpha-lac transgene (0.4 mg of alpha-lac/ml(-1) of milk). the ribozyme contains the hammerhead catalytic domain, flanked by 12-nt sequences complementary to the 3' untranslated region of bovine alpha-lac transcript. high-level expression of the ribozyme ... | 1996 | 8692881 |
| ectopic vasopressin expression in mmtv-v-ha-ras transgenic mice delays the onset of mammary tumorigenesis. | neuropeptides are often ectopically expressed by non-endocrine tumours. we used transgenic mice to assess the effect of ectopic expression of the neuropeptide, vasopressin, in mammary tumours induced by the transgenetic expression of an activated ras oncogene. mice bearing a mouse mammary tumour virus-vasopressin (mmtv-vp) fusion transgene synthesise authentic vp in mammary ducts and alveoli. bitransgenic mice bearing both mmtv-vp and mmtv-v-ha-ras transgenes developed tumours that were histolog ... | 1996 | 8695219 |
| new steroidal diazo ketones as potential photoaffinity labeling reagents for the mineralocorticoid receptor: synthesis and biological activities. | three diazo ketones in the progesterone series were synthesized as potential photoaffinity reagents. the diazo ketone group was introduced at the c17 (21-diazopregn-4-ene-3,20-dione, 1) or c13 (18-(diazomethyl)-20-hydroxypregn-4-ene-3,18-dione, 2, 18-(diazomethyl)pregn-4-ene-3, 18,20-trione, 3) position of the pregnene skeleton. whereas compound 1 could be easily obtained from the corresponding acid chloride, preparation of 2 and 3 required a less straightforward route involving reaction of tosy ... | 1996 | 8709117 |
| effects of two dietary fat levels and four dietary linoleic acid levels on mammary tumor development in balb/c-mmtv mice under ad libitum feeding conditions. | the relationship between dietary fat intake (level and type) and the development of breast cancer in humans is a matter of concern in western society. a high fat intake is associated with a greater mammary cancer risk in humans and in animal models. higher intake of polyunsaturated fatty acids in humans shows little or no association with mammary tumor development in epidemiologic surveys. from literature data, it appears that a higher intake of polyunsaturated fatty acids (linoleic acid) is rel ... | 1996 | 8710685 |
| [possible circulatory paths of endogenous human retroviruses, similar to murine mammary cancer virus]. | | 1995 | 8713343 |
| 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 |
| neonatal impaired response to viral superantigen encoded by mmtv(sw) and mtv-7. | mmtv(sw) is an exogenous mouse mammary tumor virus that codes for a superantigen sharing the same v beta specificity as mtv-7 (mis-1a). neonatal mice infected by suckling-infected milk show a deletion of the cd4+ v beta 6+ t cell subset within 8 weeks. in contrast, adult mice infected by injection of the virus in the footpad have a much faster deletion, which occurs within 2 weeks. in the present work, we investigated possible mechanisms for the different kinetics of deletion in the adult and ne ... | 1995 | 8746559 |
| conditional gene expression in secretory tissues and skin of transgenic mice using the mmtv-ltr and the tetracycline responsive system. | molecular mechanisms of development and disease can be studied in transgenic animals. controlling the spatial and temporal expression patterns of transgenes, however, is a prerequisite for the elucidation of gene function in the whole organism. previously we reported that mice carrying a tetr/vp16 hybrid gene (tta), under the control of the human cytomegalovirus immediate early 1 (hcmv-ie1) gene promoter, can be used to temporally activate the expression of transgenes under the control of a prom ... | 1995 | 8749716 |
| 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 |
| vas deferens epithelial cells in subculture: a model to study androgen regulation of gene expression. | the understanding of androgen-regulated gene expression requires a cell cultures system that mimics the functions of cells in vivo. in the present paper we have examined a vas deferens epithelial cell subculture system. cultured vas deferens epithelial cells have been shown to exhibit polarized properties characteristic of functioning epithelia and to display a high level of androgen receptors. incubation of cells with androgen caused a decrease in cellular androgen receptor mrna that was time-d ... | 1995 | 8800638 |
| deletion of cd4+ t cells by mouse mammary tumor virus (fm) superantigen with broad specificity of t cell receptor beta-chain variable region. | we previously identified a superantigen from the exogenous mouse mammary tumor virus carried by fm mice [mmtv (fm)], which can preferentially activate v beta 8.2+ cd4+ t cells by subcutaneous injection. in the present study we investigated the effect of neonatal infection with the virus on the t cell receptor (tcr) beta-chain variable region (v beta) repertoire, t cell immune response, and development of experimental allergic encephalomyelitis (eae). the infection, surprisingly, resulted in dele ... | 1996 | 8806576 |
| activated n-ras oncogene and n-ras proto-oncogene act through the same pathway for in vivo tumorigenesis. | we compared the tumorigenic effects of the n-ras oncogene and the n-ras proto-oncogene in lymphoid and mammary tissues in an in vivo model. for this purpose, we generated transgenic mice with high levels of n-ras oncogene or n-ras proto-oncogene expression, driven by the complete mouse mammary tumor virus ltr (mmtv-ltr) (mmtv/n-rast and mmtv/n-rasn constructs) and transgenic mice with low levels of n-ras oncogene or n-ras proto-oncogene expression, driven by a truncated mmtv-ltr (tmtv/n-rast and ... | 1996 | 8806695 |
| [correlation of mmtv antibody expression and risk factors of human breast cancer]. | incidence of sera with antibodies to mmtv-related proteins has been studied in a cohort at high risk for breast cancer including healthy females and those with benign breast disease. the results were evaluated versus certain risk factors of breast cancer. no significant difference in the incidence was established between cases of diffuse fibrocystic mastopathy and healthy subjects. nor was there any relationship between positive serum incidence and age, number of abortions, age at first childbir ... | 1996 | 8815632 |
| expression and presentation of endogenous mouse mammary tumor virus superantigens by thymic and splenic dendritic cells and b cells. | tolerance against superantigens (sags) encoded by endogenous mouse mammary tumor virus (mtv) loci involves the intrathymic deletion of sag-reactive t cells expressing a particular tcr v beta-chain, presumably upon presentation of the sag by specialized apc. however, although the role of dendritic cells (dc) in the induction of tolerance against conventional ags has been demonstrated, little is known about the role played by dc in tolerance induction against mtv sags. moreover, there is conflicti ... | 1996 | 8816381 |
| increased expression of the ras suppressor rsu-1 enhances erk-2 activation and inhibits jun kinase activation. | studies were undertaken to determine the effect of the ras suppressor rsu-1 on ras signal transduction pathways in two different cell backgrounds. an expression vector containing the mouse rsu-1 cdna under the control of a mouse mammary tumor virus promoter was introduced into nih 3t3 cells and the pheochromocytoma cell line pc12. cell lines developed in the nih 3t3 background expressed p33rsu-1 at approximately twice the normal endogenous level. however, pc12 cell clones which expressed p33rsu- ... | 1996 | 8816460 |
| synergistic interaction of the neu proto-oncogene product and transforming growth factor alpha in the mammary epithelium of transgenic mice. | transgenic mice expressing either the neu proto-oncogene or transforming growth factor (tgf-alpha) in the mammary epithelium develop spontaneous focal mammary tumors that occur after a long latency. since the epidermal growth factor receptor (egfr) and neu are capable of forming heterodimers that are responsive to egfr ligands such as tgf-alpha, we examined whether coexpression of tgf-alpha and neu in mammary epithelium could cooperate to accelerate the onset of mammary tumors. to test this hypo ... | 1996 | 8816486 |
| age-dependent alterations of c-fos and growth regulation in human fibroblasts expressing the hpv16 e6 protein. | normal human cells in culture become senescent after a limited number of population doublings. senescent cells display characteristic changes in gene expression, among which is a repression of the ability to induce the c-fos gene. we have proposed a two-stage model for cellular senescence in which the mortality stage 1 (m1) mechanism can be overcome by agents that bind both the product of the retinoblastoma susceptibility gene (prb)-like pocket proteins and p53. in this study we determined wheth ... | 1996 | 8817002 |
| transfection of a human topoisomerase ii alpha gene into etoposide-resistant human breast tumor cells sensitizes the cells to etoposide. | the etoposide-resistant human breast cancer cell line mda-vp was derived from mda-parent cells by sequential selection in increasing concentrations of etoposide. mda-vp cells express a lower amount of topoisomerase ii alpha mrna than the mda-parent does, have mutations in topoisomerase ii alpha (topo ii) cdna, and show cross-resistance to doxorubicin and amsacrine. we investigated whether transfer of a normal human topoisomerase ii alpha (h-topo ii) gene into mda-vp cells could overcome their re ... | 1996 | 8823806 |
| preneoplasia in mammary tumorigenesis. | | 1996 | 8826641 |
| effects of mitogens on androgen receptor-mediated transactivation. | the effects of mitogens and agents affecting tyrosine phosphorylation signaling on androgen-regulated transcription were investigated. cv-1 and hela cells were cotransfected with an androgen receptor (ar) expression vector and an androgen-responsive chloramphenicol acetyltransferase (cat) reporter gene driven by the mouse mammary tumor virus promoter. growth factors [epidermal growth factor (egf) and insulin-like growth factor i] that activate receptor tyrosine kinases, an inhibitor of phosphoty ... | 1996 | 8828495 |
| in vivo evidence for the generation of a glucocorticoid receptor-heat shock protein-90 complex incapable of binding hormone by the calmodulin antagonist phenoxybenzamine. | the glucocorticoid receptor (gr) is a ligand-regulated transcription factor whose ability to bind hormone is thought to be dependent on association with the 90-kda heat shock protein (hsp90). in the present study, we have generated a novel form of the gr, in which the receptor remains complexed to hsp90 but has lost its ability to bind hormone, by treatment of intact cells with the calmodulin (cam) antagonist phenoxybenzamine (poba). treatment of these cells, mouse l929 cells stably transfected ... | 1996 | 8838141 |
| virus-encoded superantigens. | superantigens are microbial agents that have a strong effect on the immune response of the host. their initial target is the t lymphocyte, but a whole cascade of immunological reactions ensues. it is thought that the microbe engages the immune system of the host to its own advantage, to facilitate persistent infection and/or transmission. in this review, we discuss in detail the structure and function of the superantigen encoded by the murine mammary tumor virus, a b-type retrovirus which is the ... | 1996 | 8840782 |
| transcriptional control of steroid-regulated apoptosis in murine thymoma cells. | early studies in murine t cell lines indicated that transcriptional transactivation functions encoded in the glucocorticoid receptor (gr) n-terminal domain are required for glucocorticoid-mediated apoptosis. however, more recent studies in human t cell lines have suggested that the n-terminal domain is not necessary for steroid-regulated apoptosis and that gr-mediated transrepression may be the more critical mechanism. to better understand the contribution of the gr n-terminal transactivation do ... | 1996 | 8843413 |
| wild-type p53 transgenic mice exhibit altered differentiation of the ureteric bud and possess small kidneys. | transgenic mice expressing wild-type murine p53 under the control of the mouse mammary tumor virus long terminal repeat (mmtv ltr) undergo progressive renal failure due to abnormal kidney development. similar phenotypes are observed in two transgenic lines that express wild-type p53 within the ureteric bud but not in transgenic animals expressing a dominant-negative p53 mutant allele. defective differentiation of the ureteric bud, as evidenced by altered marker expression during development, acc ... | 1996 | 8846920 |
| moderate increase in histone acetylation activates the mouse mammary tumor virus promoter and remodels its nucleosome structure. | the mouse mammary tumor virus (mmtv) promoter is regulated by steroid hormones through a hormone-responsive region that is organized in a positioned nucleosome. hormone induction leads to a structural change of this nucleosome which makes its dna more sensitive to cleavage by dnase i and enables simultaneous binding of all relevant transcription factors. in cells carrying either episomal or chromosomally integrated mmtv promoters, moderate acetylation of core histones, generated by treatment wit ... | 1996 | 8855250 |
| growth and induction kinetics of inducible and autoinducible expression of heterologous protein in suspension cultures of recombinant mouse l cell lines. | mouse ltk- cells were transfected with four different plasmids for autoinducible and highly-inducible expression of the bacterial lacz gene and cultivated in suspension. two selection genes, thymidine kinase (tk) and neomycin resistance (neor), were used to select the clones in both cell lines. the resulting two cell lines, designated m4 and r2, differ in that the inducible mmtv promoter from mouse mammary tumor virus (mmtv) controls glucocorticoid receptor (gr) gene and lacz gene expression in ... | 1996 | 8857193 |
| transfection of human topoisomerase ii alpha into etoposide-resistant cells: transient increase in sensitivity followed by down-regulation of the endogenous gene. | we have investigated the possibility of overcoming the resistance of human brain tumour cells (hbt20) to etoposide by transferring the normal human topoisomerase ii alpha (h-topo ii) gene into these cells. h-topo ii in a mammalian expression vector containing a glucocorticoid-inducible mouse mammary tumour virus (mmtv) promoter was transfected into etoposide-resistant hbt20 cells (hbt20-htop2mam). hbt20 cells transfected with pmamneo vector alone served as control cells (hbt20-mam). these were s ... | 1996 | 8870683 |
| control of endogenous mouse mammary tumor virus superantigen expression in sjl lymphomas by a promoter within the env region. | sjl mouse lymphomas (reticulum cell sarcomas, or rcss) of germinal center b cell origin express an endogenous mouse mammary tumor virus (mtv-29) superantigen (vsag) that stimulates vbeta16+ t cells to produce cytokines essential for rcs growth. normal or lps-activated sjl/j b cells contain two to three larger mrnas for mouse mammary tumor virus-long terminal repeat (ltr) but not the 1.8-kb mrna, which is prominent in rcs cells and encodes the vsag-29. mrnas from rcs and normal lymphoid cells wer ... | 1996 | 8871650 |
| the origin of sl family mice. | the origin of sl family mice was studied by analyzing 100 microsatellite loci, the major histocompatibility complex, the mx gene, murine leukemia provirus, and mammary tumor provirus. from the genetic profile of family members and their history, we assumed the existence of a proto-sl mouse, an ancestor of all sl family members. many alleles were contributed to the proto-sl by the ancestors related to strains a2g and cf#1, and/or some wild mice. among four existing family members, sl/am and sl/ni ... | 1996 | 8872992 |
| superantigens of mouse mammary tumour virus: implications for diabetes? | | 1996 | 8877280 |
| cd4 expression is important but not essential for infection with exogenous mouse mammary tumor virus. | we studied local events in the popliteal lymph nodes of cd4-deficient mice following foot pad injection with an mmtv strain which carries the gene for a v beta 14-specific superantigen. injection of the v beta 14-specific mmtv induced vigorous expansion of v beta 14+ cd4+ t cells and b cells in their lymph nodes of cd4+/- heterozygous control mice. on the other hand, cd4-/- mice injected with the mmtv showed a proliferation of v beta 14+ t cells among the population of tcr alpha beta + cd4-cd8- ... | 1996 | 8877410 |
| mechanisms in interleukin-2 protection against glucocorticoid-induced apoptosis: regulation of ap-1 and glucocorticoid receptor transcriptional activities. | we have used the gibbon ape leukemia cell line mla-144 and its corticoid-sensitive subclone mla-e7t to analyze the mechanisms whereby interleukin-2 (il-2) can protect t cells against dexamethasone-induced apoptosis. mla cells are characterized by the constitutive expression of intermediate affinity receptors for il-2, together with il-4 receptors. mla-144 cells secrete il-2 and are insensitive to dexamethasone, whereas mla-e7t cells do not constitutively produce significant amounts of il-2 and u ... | 1996 | 8877731 |
| hormonal control of transcription from two mammary specific promoters in a rat mammary epithelial cell line. | | 1996 | 8878895 |
| proteolytic processing activates a viral superantigen. | mouse mammary tumor virus (mmtv) superantigens (vsag) undergo proteolytic processing at residues that have been demonstrated in vitro to be recognition sites for the endoprotease furin. to examine the role of furin in the presentation of vsag7 to t cells, the vsag7 and class ii mhc iek genes were introduced into chinese hamster ovary (cho) cells (furin-positive) and into a furin-negative cho variant (fd11). both transfected cell lines efficiently presented peptide antigen and bacterial superanti ... | 1996 | 8879228 |
| androgenic up-regulation of androgen receptor cdna expression in androgen-independent prostate cancer cells. | the expression of the androgen receptor (ar) gene is regulated by androgens. although androgens down-regulate ar mrna in most cell lines and tissues, including the prostate, up-regulation occurs in some tissues. androgen-mediated reduction in ar mrna is reproduced in cos1 cells and in the androgen-sensitive human prostate cancer cell line lncap when each expresses the ar cdna. we have previously established that the ar cdna contains the requisite sequences for this down-regulation. here we shown ... | 1996 | 8883219 |
| growth and differentiation of c2 myogenic cells are dependent on serum response factor. | in order to study to what extent and at which stage serum response factor (srf) is indispensable for myogenesis, we stably transfected c2 myogenic cells with, successively, a glucocorticoid receptor expression vector and a construct allowing for the expression of an srf antisense rna under the direction of the mouse mammary tumor virus long terminal repeat. in the clones obtained, srf synthesis is reversibly down-regulated by induction of srf antisense rna expression by dexamethasone, whose effe ... | 1996 | 8887636 |
| control of proinsulin production by sense-anti-sense regulation in response to glucocorticoids. | one difficulty involved in gene therapy for diabetes is a control of proinsulin production by the cells transfected with insulin cdna. the introduction of a feedback mechanism to control the expression of the introduced gene based on the host's need for insulin is one possible treatment approach. to control proinsulin production at a transcriptional level, we introduced a glucocorticoid responsive promoter in the 3' region of insulin cdna in reverse orientation (pbcmgs-neo-ins-invmmtv) so that a ... | 1996 | 8889233 |
| dominant inhibitory ras delays sindbis virus-induced apoptosis in neuronal cells. | mature neurons are more resistant than dividing cells or differentiating neurons to sindbis virus-induced apoptotic death. therefore, we hypothesized that mitogenic signal transduction pathways may influence susceptibility to sindbis virus-induced apoptosis. since ras, a 21-kda gtp-binding protein, plays an important role in cellular proliferation and neuronal differentiation, we investigated the effect of an inducible dominant inhibitory ras on sindbis virus-induced death of a rat pheochromocyt ... | 1996 | 8892895 |
| endogenous mtv-encoded superantigens are not required for development of murine aids. | immune activation in murine aids (maids) has been suggested to involve a superantigen (sag). the possibility that sags encoded by mammary tumor virus (mtv) might be the source of stimulation was studied by using mtv mice. mtv- mice developed typical maids, excluding a requirement for mtv-encoded sags in the pathogenesis of this disorder. | 1996 | 8892943 |
| effect of ethanol and cocaine treatment of the immune system of v-ha-ras-transgenic mice. | the objective was to investigate if the presence of the v-ha-ras oncogene could induce immune changes different to the ones observed in normal mice. therefore, we decided to use oncomice, the transgenic mice with an activated v-ha-ras oncogene under the control of the mouse mammary tumor virus-promoter, and their normal inbred counterparts, fvb mice. both strains of mice were fed the lieber-decarli liquid diet with ethanol or the isocaloric control diet and were injected daily with cocaine or sa ... | 1996 | 8894804 |
| metastasis of mammary carcinomas in grs/a hybrid mice transgenic for the mts1 gene. | transgenic mice, carrying the mts1 gene, one of the genes involved in the acquisition of the metastatic phenotype, were generated. the mts1 gene was placed under the control of the mouse mammary tumor virus (mmtv) long terminal repeat (ltr) promoter leading to overexpression in the lactating mammary gland of transgenic animals. animals bearing the transgene appear phenotypically normal. animals of two transgenic lines (tg463 and tg507) were crossed with the grs/a mice. the grs/a strain is charac ... | 1996 | 8895507 |
| expression of the calcium-binding protein s100a4 (p9ka) in mmtv-neu transgenic mice induces metastasis of mammary tumours. | increased levels of s100a4 (p9ka) confer metastatic ability on a normally non-metastatic epithelial cell line. to find out whether s100a4 can induce metastasis in vivo, transgenic mice expressing high levels of s100a4, but which show no phenotypic effect, have been mated with mmtv-neu transgenic mice which succumb to stochastic mammary neoplasia related to expression of the mmtv-neu transgene. resultant bitransgenic, multiparous, female progeny expressing both s100a4 and neu have a slightly earl ... | 1996 | 8895508 |
| resistance to glucocorticoid-induced apoptosis in human t-cell acute lymphoblastic leukemia cem-c1 cells is due to insufficient glucocorticoid receptor expression. | the ability of glucocorticoids (gcs) to induce death in lymphoid-origin cells is the basis for their frequent use in the therapy of various human hematological malignancies. however, the occurrence of primary or secondary gc resistance limits their clinical usefulness. prior investigations into the mechanism of gc resistance in established human leukemic cell lines revealed loss-of-function mutations in the gc receptor (gr) gene. in this study, we analyzed the gc-resistant human acute t-cell leu ... | 1996 | 8895760 |