| chemoprevention of mammary tumor virus-induced and chemical carcinogen-induced rodent mammary tumors by natural plant products. | the natural plant products turmeric, beta-carotene, catechin, and betel leaf extract were evaluated for their antitumor effects on mammary tumorigenesis in murine mammary tumor expressing c3h (jax) mice and in wistar rats treated with the chemical carcinogen 7-12-dimethylbenz(a)anthracene (dmba). administration of turmeric through the diet and of beta-carotene, catechin, and betel leaf extract through the drinking water to virgin female c3h mice resulted in decreased tumor incidence and tumor bu ... | 1994 | 7526904 |
| [analysis of effectiveness of cdna synthesis, induced using complementary primers and primers containing a noncomplementary base matrix]. | we have studied the efficiency of dna synthesis catalyzed by m-mlv reverse transcriptase or thermus aquaticus dna polymerase for primers (4-17 nucleotides long) either completely matched or possessing a single mismatched base pair at all possible positions in the primer. it has been shown that dna synthesis efficiency depends not only on the position of mismatched base pair but on the length and primary structure of the primer. the enzyme, template, and primer concentrations determine the relati ... | 1994 | 7527482 |
| evidence for superantigen activity of the bel 3 protein of the human foamy virus. | the human foamy virus is a complex retrovirus that codes for several regulatory bel genes in addition to the conventional gag, pol, and env genes. the bel 3 gene is located in the 3' part of the viral genome comparable to that of the superantigen of the mouse mammary tumor virus. superantigens bound to major histocompatibility complex (mhc) class ii molecules have been shown to stimulate t cells in a v beta-specific manner. the recombinant bel 3 protein purified to near homogeneity was assayed i ... | 1994 | 7528260 |
| the majority of postselection cd4+ single-positive thymocytes requires the thymus to produce long-lived, functional t cells. | we have previously isolated, and characterized in vitro, two subsets of cd4hi t cell receptor (tcr)hi single positive (sp) thymocytes: cd8- and cd8lo. in this report, we have analyzed phenotypic, functional, and developmental characteristics of these "late" cd4hi sp thymocyte subsets. the tcrhi phenotype and the elimination of t cells expressing tcr v beta segments reactive with endogenous mouse mammary tumor virus (mmtv) products suggested that both subsets had undergone positive and negative s ... | 1995 | 7528769 |
| modulation of glucocorticoid-regulated transcription by purines: novel characteristics and implications for tissue specificity of steroid responses. | treatment of the t47d(a1-2) mammary carcinoma cell line with the nonspecific kinase inhibitor 2-aminopurine (2ap) has an unusual effect on induction of the mouse mammary tumor virus promoter by glucocorticoids. 2ap initially abrogates the dexamethasone-mediated increase, but after about 16-20 h, this effect is reversed, and continued incubation with 2ap potently stimulates the hormone induction. the biphasic kinetics of 2ap action displayed cell specificity. no inhibitory phase was seen in fibro ... | 1995 | 7532578 |
| inhibition of 3t3-l1 adipose differentiation by 2,3,7,8-tetrachlorodibenzo-p-dioxin. | 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd)-induced toxicity is particularly striking in adipose tissue, where it causes severe wasting. this phenomenon suggests that tcdd could have effects on adipocyte differentiation, now demonstrated using 3t3-l1 cells as a model system. when cells were treated with 10 nm tcdd before differentiation or during the first two days of induction in the presence of dexamethasone (dex) and isobutylmethylxanthine (ibmx), a reduction occurred in the number of fat cell ... | 1995 | 7537747 |
| cyclosporin a potentiates the dexamethasone-induced mouse mammary tumor virus-chloramphenicol acetyltransferase activity in lmcat cells: a possible role for different heat shock protein-binding immunophilins in glucocorticosteroid receptor-mediated gene expression. | as previously observed for fk506, we report here that cyclosporin a (csa) treatment of mouse fibroblast cells stably transfected with the mouse mammary tumor virus-chloramphenicol acetyltransferase (mmtv-cat) reporter plasmid (lmcat cells) results in potentiation of dexamethasone (dex)-induced cat gene expression. potentiation by csa is observed in cells treated with 10-100 nm dex but not in cells treated with 1 microm dex, a concentration of hormone which results in maximum cat activity. at 10 ... | 1995 | 7539138 |
| non-exclusive fas control and age dependence of viral superantigen-induced clonal deletion in lupus-prone mice. | to investigate the role of fas in the induction of tolerance by viral superantigen (sag), we infected mrl-+/+ and mrl-lpr (fas mutant) mice with mouse mammary tumor virus (mmtv) (sw), a virus encoding an sag with the same specificity as endogenous mtv-7-sag. in normal mice, this infection has two distinct consequences on specific v beta 6+cd4+ t cells, consisting of activation followed by clonal deletion. mmtv (sw)-sag-induced activation in vivo was identical in mrl-+/+ and mrl-lpr mice. in cont ... | 1995 | 7542196 |
| direct physical interaction involving cd40 ligand on t cells and cd40 on b cells is required to propagate mmtv. | the propagation of mouse mammary tumor virus (mmtv) has been analyzed in mice defective for expression of cd40 ligand (cd40l). mice with endogenous viral superantigen (sag) delete t cells with cognate v beta independent of cd40l expression. nevertheless, cd40l-mice do not show deletion of cognate t cells after being exposed to infectious mmtv and have greatly diminished viral replication. the response of cd40l- t cells to sag in vitro is also impaired, but can be reconstituted by adding b cells ... | 1995 | 7542547 |
| high-affinity ssdna inhibitors of the reverse transcriptase of type 1 human immunodeficiency virus. | the reverse transcriptase (rt) of hiv-1 is a plausible target for therapeutic agents aimed at inhibiting propagation of the virus. we have used "irrational drug design", that is, combinatorial chemistry with oligonucleotide libraries, to identify high-affinity ligands aimed at hiv-1 rt. the methodology, termed selex (systematic evolution of ligands by exponential enrichment), was employed with a single-stranded dna library. the selected ssdna ligands bind hiv-1 rt with kd values as low as 1 nm a ... | 1995 | 7542922 |
| identification of three human sequences with viral superantigen-specific primers. | the open reading frame (orf) in the long terminal repeat (ltr) of mouse mammary tumor virus (mmtv) has recently been shown to encode multiple products including a negative acting factor (naf) and a superantigen (sag). expression of superantigens from endogenous mmtv loci in the mouse results in the deletion of whole classes of t cells. in a pcr approach, with primers to the mmtv orf and hybridization to mmtv specific probes, we have identified three human sequences. direct sequencing of pcr prod ... | 1995 | 7542948 |
| induction of mammary epithelial hyperplasias and mammary tumors in transgenic mice expressing a murine mammary tumor virus/activated c-src fusion gene. | activation of the c-src tyrosine kinase has been implicated as an important step in the induction of mammary tumors in both mice and humans. to directly assess the effect of mammary gland-specific expression of activated c-src, we established transgenic mice that carry a constitutively activated form of c-src under transcriptional control of the murine mammary tumor virus long terminal repeat. female mice derived from several independent transgenic lines lactate poorly as a consequence of an imp ... | 1995 | 7544006 |
| constitutive expression of a truncated int3 gene in mouse mammary epithelium impairs differentiation and functional development. | int3 is interrupted by retroviral dna insertion in approximately 18% of primary czech mouse mammary tumors induced by mouse mammary tumor virus. one consequence of these insertions is the production of a 2.4-kilobase, tumor-specific rna transcript encoding the entire intracellular domain of the int3 protein which is initiated from the 3' long terminal repeat promoter of the inserted viral genome. female mice (fvb-3) transgenic for a genomic fragment comprised of this truncated region of int3 exp ... | 1995 | 7544153 |
| human endogenous retrovirus k does not encode mouse mammary tumor virus-related antigens in human breast carcinomas. | | 1995 | 7546915 |
| fgf-8 isoforms differ in nih3t3 cell transforming potential. | we previously identified fgf-8 as a frequently activated gene in tumors from mouse mammary tumor virus-infected wnt-1 transgenic mice, suggesting that fgf-8 is a proto-oncogene. we further determined that multiple, secreted protein isoforms that differ at their mature amino termini are encoded by alternatively spliced mrnas transcribed from the gene. we now present evidence that there are differences in the potency of nih3t3 cell transformation displayed by three of the fgf (fibroblast growth fa ... | 1995 | 7547503 |
| nucleosomes reconstituted in vitro on mouse mammary tumor virus b region dna occupy multiple translational and rotational frames. | the mouse mammary tumor virus acquires a highly reproducible chromatin structure when integrated into cellular dna. previous studies have suggested that the ltr is arranged as a series of six phased nucleosomes, that occupy specific positions on the ltr. on the basis of nucleosome reconstitution studies using dna from the b region of the ltr, it has been argued that this sequence directs a uniquely positioned nucleosome. here we demonstrate in vitro that reconstituted b region nucleosomes adopt ... | 1995 | 7547993 |
| the chromosomal location of the mouse mammary tumor gene int6 and related pseudogenes in the mouse genome. | the int6 gene is a common insertion site for the mouse mammary tumor virus (mmtv) in mouse mammary tumors. we have determined that this gene is located centromeric of the myc protooncogene on mouse chromosome 15. in the mouse genome there are several other int6-reactive restriction fragments that are located on mouse chromosomes 6, 11, 14, 17, and 18. nucleotide sequence analysis of four of six of these additional int6 fragments showed that they contain processed int6 pseudogenes. comparisons be ... | 1995 | 7558022 |
| superantigenic characteristics of mouse mammary tumor viruses play a critical role in susceptibility to infection in mice. | mouse mammary tumor viruses (mmtv) are retroviruses that induce mammary carcinomas. an interesting feature of these viruses is the superantigen (sag) encoded in an open reading frame within the 3' long terminal repeat. the mechanism by which ingestion of milk-borne virus results in infection of the host mammary tissue remains incompletely understood. however, a working model has been proposed in which the interaction between viral sag, t-cell receptor and mhc class ii i-e facilitates viral repli ... | 1995 | 7561341 |
| a maternally-inherited alteration in the t cell repertoire of balb/c mice. | a number of milk-borne exogenous mammary tumor viruses (mmtv) infect mice shortly after birth and, when expressed, produce superantigens. the expression of these superantigens mediate the progressive deletion of t cells expressing specific v beta products. here we describe a maternally-inherited alteration in the t cell repertoire in one colony of balb/c mice which has not been reported up to now. this alteration involves the deletion of v beta 2+ and 14+ cd4+ t cells and correlates with a high ... | 1995 | 7565035 |
| stimulation of mouse mammary tumor virus superantigen expression by an intragenic enhancer. | the mechanisms regulating expression of mouse mammary tumor virus (mmtv)-encoded superantigens from the viral sag gene are largely unknown, due to problems with detection and quantification of these low-abundance proteins. to study the expression and regulation of the mmtv sag gene, we have developed a sensitive and quantitative reporter gene assay based on a recombinant superantigen-human placental alkaline phosphatase fusion protein. high sag-reporter expression in ba/f3, an early b-lymphoid c ... | 1995 | 7568120 |
| clonal variations among multiple primary mammary tumors and within a tumor of individual mice: insertion mutations of int oncogenes. | laboratory mice infected with the mouse mammary tumor virus (mmtv) often develop multiple mammary tumors. however, no comprehensive studies have been done addressing the question of whether or not different primary tumors of individual mice are related ontogenetically to each other. further, it is not known to what extent individual tumors vary in their cellular composition. we, therefore, examined intertumor and intratumor patterns of the rearrangements in int-1 (wnt-1), int-2 (fgf-3), and int- ... | 1995 | 7571419 |
| [the regulation of calmodulin in the cell cycle]. | in order to study the role of calmodulin (cam) in the cell cycle, rc 3 cells carring the cam expression vectors which was constructed by joining the cam cdna with a plasmid of mouse mammary tumor virus (mmtv), were used in this experiment. the cam expression vectors transcription is regulated by a dexamethasone (dxm) inducible mmtv ltr promoter. upon addition of dxm, cells have transiently increased cam mrna and protein levels. increased cam caused a acceleration of proliferation. flow cytometri ... | 1995 | 7571946 |
| a bispecific antibody prolongs survival in mice bearing lung metastases of syngeneic mammary adenocarcinoma. | in the present study we tested whether t cells retargeted with a bispecific antibody (bsab) could block the growth of lung metastases of syngeneic mammary adenocarcinoma in immunocompetent mice. balb/c mice were injected i.v. with tumor and i.p. with a genetically engineered bispecific f(ab')2 [bs(fab')2] having specificity for murine cd3 epsilon chain and for the gp52 mouse mammary tumor viral glycoprotein, which is expressed on the tumor cells. the bs(fab')2 was physically stable in blood and ... | 1995 | 7577803 |
| cysteines 638 and 665 in the hormone binding domain of human glucocorticoid receptor define the specificity to glucocorticoids. | to understand the function of cysteines, we have substituted cysteines 638, 643, and 665 by serine in the hormone-binding domain (hbd) of the human glucocorticoid receptor (hgr). in hormone-binding assays using [3h]dexamethasone, hgr c643s and hgr c665s exhibited wild type receptor kd of 2.5 nm and hgr c665sm666l displayed a kd of 3.7 nm, while hgr c638s exhibited a kd of 162 pm, a 15-fold higher affinity. the affinity of hgr c638s for ru486 was 10-fold higher, and the mutants c643s and c665s bo ... | 1995 | 7578014 |
| localization of the mouse mammary tumor provirus, mtv44, on chromosome 11. | | 1995 | 7579890 |
| human androgen insensitivity due to point mutations encoding amino acid substitutions in the androgen receptor steroid-binding domain. | mutations of the human androgen receptor gene were identified in five subjects from four families with androgen insensitivity syndrome. individual exons of the androgen receptor gene were amplified by the polymerase chain reaction from genomic dna and screened for sequence-dependent differences in their melting characteristics by denaturing gradient gel electrophoresis. dna fragments from exons with altered mobility were sequenced. four different single nucleotide base substitutions were found w ... | 1995 | 7581399 |
| local regression of breast tumors following intramammary ganciclovir administration in double transgenic mice expressing neu oncogene and herpes simplex virus thymidine kinase. | females from a mouse lineage transgenic for the activated rat neu oncogene under the control of the mouse mammary tumor virus (mmtv) long terminal repeat (ltr) all develop breast tumors with high reproducibility within the first 2-3 months of life. these animals were crossed with mice from a lineage transgenic for the herpes simplex virus thymidine kinase gene (hsvtk) under the control of its own promoter and polyoma enhancer. double transgenic mice (for both neu and tk) developed breast neoplas ... | 1995 | 7584128 |
| a target for tumour-directed therapy. | | 1995 | 7585140 |
| prevention of breast tumour development in vivo by downregulation of the p185neu receptor. | certain strains of transgenic mice that express the rat neu oncogene (neut) in mammary epithelial cells develop breast tumours at an average of 44 weeks of age. in this study, intraperitoneal injection of a monoclonal anti-receptor antibody specific for the rat neut oncogene product dramatically affected tumour development in these transgenic mice in a dose-dependent manner. a significant proportion (50%) of mice, when injected with anti-receptor antibodies, did not develop tumours even after 90 ... | 1995 | 7585144 |
| detection of mammary tumor virus env gene-like sequences in human breast cancer. | mouse mammary tumor virus (mmtv) has been related to human breast cancer (bc) in previous studies. although suggestive sequence homology to mmtv has been described in bc dna, the presence of human endogenous retroviruses (hers) confounded these results. we have selected a 660-bp sequence of the mmtv env gene with very low homology to her or to any other human or viral gene. we have searched for sequences homologous to it using the polymerase chain reaction. dna was extracted from fresh or frozen ... | 1995 | 7585568 |
| llc-pk1 cells model 11 beta-hydroxysteroid dehydrogenase type 2 regulation of glucocorticoid access to renal mineralocorticoid receptors. | mineralocorticoid receptors (mrs) are nonselective in vitro, binding corticosterone, cortisol, and aldosterone with similar affinity. in the distal nephron in vivo, mrs are selectively activated by aldosterone despite much higher glucocorticoid levels. this has been suggested to reflect the action of 11 beta-hydroxysteroid dehydrogenase (11 beta-hsd), which catalyzes rapid inactivation of corticosterone to 11-dehydrocorticosterone (cortisol to cortisone). however, cellular models of this effect ... | 1995 | 7588309 |
| the mineralocorticoid activity of progesterone derivatives depends on the nature of the c18 substituent. | to investigate the role of the c18 substituents in the agonist/antagonist properties of mineralocorticoids, the activities of certain c18-substituted progesterone (p) derivatives were examined. these compounds were characterized by an unsaturated side-chain in the case of 18-vinylprogesterone (18vp) and 18-ethynylprogesterone (18ep) and by an enone group in the case of 18-oxo-18-vinylprogesterone (18ovp). p and its 18-substituted derivatives bind to the recombinant human mr (hmr) overexpressed i ... | 1995 | 7588320 |
| quantitation of endogenous mouse mammary tumor virus superantigen expression by lymphocyte subsets. | superantigens (sag) encoded by endogenous mouse mammary tumor viruses (mtv) interact with the v beta domain of the t cell receptor (tcr-v beta). presentation of mtv sag can lead to stimulation and/or deletion of the reactive t cells, but little is known about the quantitative aspects of sag presentation. although monoclonal antibodies have been raised against mtv sag, they have not been useful in quantitating sag protein, which is present in very low amounts in normal cells. alternative attempts ... | 1995 | 7589137 |
| i-j revisited: is the i-j genetic restriction in downregulation due to an endogenous superantigen analogous to mammary tumour virus (mtv)-encoded endogenous superantigen? | this article puts forward the hypothesis that the i-j genetic restriction observed between certain downregulatory (suppressor) t cells and antigen presenting cells is due to an endogenous superantigen analogous to the mouse mammary tumour virus (mtv) products encoded by the open reading frames in the 3' long terminal repeat (ltr) of mtv's. in its weak form this hypothesis asserts that the i-j genetic restriction is due to an endogenous superantigen ligand on antigen presenting cells, which cross ... | 1994 | 7589693 |
| fibroblast growth factor 3 is tumorigenic for mouse mammary cells orthotopically implanted in nude mice. | fibroblast growth factor-3 (fgf-3) is involved in mouse mammary tumorigenesis since the fgf-3 gene is a main target for mouse mammary tumor virus (mmtv) insertional activation. its action has been correlated with the appearance of pregnancy-dependent tumors. we describe here the effects on normal mouse mammary ef43 cells of the short fgf-3 protein form which enters the secretory pathway. the genes, fgf-3 aug or fgf-4 for comparison, were introduced in the mammary cells by means of retroviral vec ... | 1995 | 7591288 |
| cellular factors binding to a novel cis-acting element mediate steroid hormone responsiveness of mouse mammary tumor virus promoter. | steroid hormone receptors regulate mouse mammary tumor virus (mmtv) gene expression by binding to hormone response dna elements present in the long terminal repeat. tissue-specific expression of mmtv is unlikely to be regulated by steroid hormone-receptor complex alone, and mammary cell-specific factors might play a role in the hormone-induced transcriptional activation. in this report we have investigated the function of a novel cis-acting element designated kil (-204 to -188) which is located ... | 1995 | 7592667 |
| protein-tyrosine phosphatase epsilon. an isoform specifically expressed in mouse mammary tumors initiated by v-ha-ras or neu. | transgenic mice that overexpress v-ha-ras, c-myc, c-neu or int-2 proto-oncogenes in the mammary epithelium develop breast tumors with morphologies that are characteristic of each initiating oncogene. since these morphological differences reflect distinctive patterns of tumor-specific gene expression, the identification of the products of these genes might shed light on the mechanisms of transformation and/or the identity of target cells that are transformed by specific classes of oncogenes. by f ... | 1995 | 7592814 |
| high level monocyte chemoattractant protein-1 expression in transgenic mice increases their susceptibility to intracellular pathogens. | we have constructed transgenic mice in which the mouse mammary tumor virus long terminal repeat controls the expression of murine monocyte chemoattractant protein-1 (mcp-1). several independently derived lines of transgenic mice constitutively expressed mcp-1 protein in a variety of organs. protein extracts from these organs had substantial in vitro monocyte chemoattractant activity that was neutralized by an anti-mcp-1 ab, indicating that transgenic mcp-1 protein is biologically active. however ... | 1995 | 7594486 |
| differences in the avidity of tcr interactions with a superantigenic ligand affect negative selection but do not allow positive selection. | the products of the sag genes of the exogenous mouse mammary tumor virus (mmtv) genome and of endogenous mtv integrants have been demonstrated to affect the t cell repertoire in mice by causing the deletion of t cells expressing receptors encoded by particular v beta gene segments. since these deletions affect large populations of t cells with receptors of heterogeneous specificity, they serve as an important model for the study of t cell development in normal mice. using several c3h/hen-based s ... | 1995 | 7594520 |
| the use of mammary tumor virus (mtv)-negative and single-mtv mice to evaluate the effects of endogenous viral superantigens on the t cell repertoire. | most laboratory strains of mice have between two and eight endogenous superantigens. these viral superantigens (vsags) are coded by genes in the 3' long terminal repeats of endogenous mammary tumor viruses (mtv's). a line of mtv-negative mice and several lines of mice containing single mtv's were created by inbreeding the f2 progeny of cba/caj and c58/j mice, which have no mtv integrants in common. this allowed the t cell repertoire of h-2k mice, unaffected by mtv superantigens, as well as the e ... | 1995 | 7595219 |
| dietary lipids and calorie restriction affect mammary tumor incidence and gene expression in mouse mammary tumor virus/v-ha-ras transgenic mice. | we have studied the effects of food restriction (fr) and substitution of fish oil (fo; omega 3) for corn oil (co; omega 6) on breast tumor incidence and survival in mouse mammary tumor virus/v-ha-ras transgenic (onco) mice. the diets were as follows: group 1, 5% (wt/wt) co fed ad libitum (al); group 2, 5% co, restricted calories (40% fewer calories than al; fr); group 3, 20% co fed al; and group 4, 20% fo fed al. after 3 years, 40% of fr onco (group 2) mice were alive, whereas there were no surv ... | 1995 | 7604020 |
| increase of skeletal muscle relaxation speed by direct injection of parvalbumin cdna. | parvalbumin (pv) is a high affinity ca(2+)-binding protein found at high concentration in fast-contracting/relaxing skeletal muscle fibers of vertebrates. it has been proposed that pv acts in the process of muscle relaxation by facilitating ca2+ transport from the myofibrils to the sarcoplasmic reticulum. however, on the basis of metal-binding kinetics of pv in vitro, this hypothesis has been challenged. to investigate the function of pv in skeletal muscle fibers, direct gene transfer was applie ... | 1995 | 7604022 |
| a genetic screen identifies cellular factors involved in retroviral -1 frameshifting. | to identify cellular factors that function in -1 ribosomal frameshifting, we have developed assays in the yeast saccharomyces cerevisiae to screen for host mutants in which frameshifting is specifically affected. expression vectors have been constructed in which the mouse mammary tumor virus gag-pro frameshift region is placed upstream of the lacz gene or the cup1 gene so that the reporters are in the -1 frame relative to the initiation codon. these vectors have been used to demonstrate that -1 ... | 1995 | 7604038 |
| detection of retroviral superantigen and products of the envelope gene from endogenous mouse mammary tumor virus in b cells from balb/c mice. | minor lymphocyte-stimulating antigens and other superantigens have been shown to be encoded by the 3' long terminal repeat (ltr) open reading frame (orf) of the endogenous and exogenous mammary tumor viruses. we have previously reported the presence of an antigen(s) related to mouse mammary tumor virus (mmtv) env products in splenic b cells of balb/c mice. by western blots an mmtv-related molecule of 68 kda was detected in splenic preparations of b lymphocytes, but not in t cells. antibodies aga ... | 1995 | 7606792 |
| degradation of endothelial cell matrix collagen is correlated with induction of stromelysin by an activated ras oncogene. | a conditional expression system was established whereby the human k-ras, v-src, and v-mos genes were cloned into a conditional expression vector downstream of the dexamethasone-inducible mouse mammary tumor virus long terminal repeat. rat-1 fibroblasts were transfected with these constructs and selected in medium containing g418. cloned transfectants were isolated and characterized for absolute dependence on dexamethasone for expression of oncogene products and anchorage-independent growth in so ... | 1995 | 7606886 |
| stimulation of basal transcription from the mouse mammary tumor virus promoter by oct proteins. | the steroid hormone-inducible promoter of mouse mammary tumor virus (mmtv) contains three overlapping sequences related to the consensus octamer motif atgcaaat. basal promoter activity in the absence of hormone induction from a template in which all three octamer elements were mutated was decreased by two-to threefold in in vitro transcription assays. oct-1 protein purified from hela cell nuclear extracts, as well as recombinant oct-1 expressed in bacteria, recognized mmtv octamer-related sequen ... | 1995 | 7609037 |
| triple helix dna alters nucleosomal histone-dna interactions and acts as a nucleosome barrier. | oligonucleotides which form triple helical complexes on double-stranded dna have been previously reported to selectively inhibit transcription both in vitro and in vivo by physically blocking rna polymerase or transcription factor access to the dna template. here we show that a 16mer oligonucleotide, which forms triple helix dna by binding to a 16 bp homopurine segment, alters the formation of histone-dna contacts during in vitro nucleosome reconstitution. this effect was dna sequence-specific a ... | 1995 | 7610046 |
| dexamethasone inducible gene expression optimised by glucocorticoid antagonists. | | 1995 | 7610066 |
| superantigens of mouse mammary tumor virus. | superantigens (sags) are proteins of microbial origin that bind to major histocompatibility complex (mhc) class ii molecules and stimulate t cells via interaction with the v beta domain of the t cell receptor (tcr). mouse mammary tumor virus (mmtv) is a milk-transmitted type b retrovirus that encodes a sag in its 3' long terminal repeat. upon mmtv infection, b cells present sag to the appropriate t cell subset, which leads to a strong "cognate" t-b interaction. this immune reaction results in pr ... | 1995 | 7612231 |
| activation of a mmtv/mdr3 fusion transcript from a cryptic viral promoter is stimulated by mdr-derived sequences located in intron i. | in p388/vcr-10 cells, resistance to cytotoxic drugs is caused by the overexpression of the mdr3 gene, in absence of gene amplification. the gene is transcriptionally activated following integration of a full-length mouse mammary tumor virus (mmtv) within intron i, upstream of the coding region of the gene. this integration results in the production of mmtv/mdr3 fusion transcripts that originate from the antisense 5'ltr of the provirus. the mechanism of mdr3 activation in these cells remains uncl ... | 1995 | 7618265 |
| effect of increased glucocorticoid responsiveness in transformed mouse lung cells. | many transformed mouse lung cells, including lm2 cells, contain activating mutations in the ki-ras gene and show reduced responsiveness to growth inhibition by glucocorticoids. lm2gr cells, which are lm2 cells stably transfected with a rat glucocorticoid receptor (gr) gene, were used to determine whether increasing glucocorticoid responsiveness can influence aspects of the transformed phenotype. lm2gr cells grew slower and had a lower final saturation density than the parental lm2 cells. express ... | 1995 | 7619216 |
| t cell repertoire and clonal deletion of mtv superantigen-reactive t cells in mice lacking cd4 and cd8 molecules. | cd4-cd8- double-negative t cells constitute a lymphocyte subpopulation within the thymus and peripheral lymphatic organs that express a unique t cell receptor (tcr) repertoire and do not undergo negative selection. to test whether these cells develop as a distinct lineage or due to altered selection in the absence of cd4 and cd8 expression, we analyzed the tcr repertoire in mice lacking both cd4 and cd8 accessory molecules after homologous recombination (cd40/0cd80/0). we show that mature t cell ... | 1995 | 7621886 |
| the mmtv/c-myc transgene and p53 null alleles collaborate to induce t-cell lymphomas, but not mammary carcinomas in transgenic mice. | a number of properties of the cancer-related genes c-myc and p53 suggest that they might collaborate to induce tumorigenesis. to test this notion, we produced doubly heterozygotic mice bearing disrupted p53 alleles and a fusion transgene consisting of the mouse mammary tumor virus (mmtv) ltr and the oncogene c-myc. mice bearing both the mmt/c-myc transgene and a single p53- allele develop very aggressive pre-t- and t-cell lymphomas with a significantly shorter latency than mice carrying either t ... | 1995 | 7624126 |
| steroid hormone receptor status defines the mmtv promoter chromatin structure in vivo. | the ability to respond to small signalling molecules such as steroid hormones is important for many physiological processes. steroid hormones act through a group of high affinity receptors that regulate transcription by binding to hormone response elements (hres) located within the promoters of target genes, which themselves are organized with nuclear proteins to form chromatin. to dissect the mechanisms(s) of steroid hormone action we have used the steroid inducible mouse mammary tumor virus (m ... | 1995 | 7626491 |
| fatty acid activation of peroxisome proliferator-activated receptor (ppar). | peroxisome proliferators such as clofibric acid, nafenopin, and wy-14,643 have been shown to activate peroxisome proliferator-activated receptor (ppar), a member of the steroid nuclear receptor superfamily. we have cloned the cdna from rat that is homologous to that from mouse, which encodes a 97% similar protein. to search for physiologically occurring activators, we established a transcriptional transactivation assay by stably expressing in cho cells a chimera of rat ppar and the human glucoco ... | 1995 | 7626496 |
| the effect of various introns and transcription terminators on the efficiency of expression vectors in various cultured cell lines and in the mammary gland of transgenic mice. | various combinations of promoters, introns and transcription terminators were used to drive the expression of bovine growth hormone (bgh) cdna in different cell types. in constructs containing the human cytomegalovirus (hcmv) promoter and the sv40 late genes terminator, the intron from sv40 genes (vp1) was much more efficient, than the intron from the early genes (t). the synthetic intron sis generated by the association of an adenovirus splice donor and an immunoglobulin g splice acceptor showe ... | 1995 | 7632393 |
| structure of the int-5, a novel mmtv integration genomic locus containing mouse early transposon ltr homology region. | previous studies have reported the cloning and identification of the int-5, a novel mouse mammary tumor virus (mmtv) integration locus involved in mammary tumorigenesis. here we report the characterization of the 5.5 kb region from this novel mmtv integration site. our results show that the region after the mmtv integration site, a 258 bp sequence is homologous (100%) to the mouse early transposon (metn) long-terminal repeat and other sequences of the this transposon are not present in the 5.5 k ... | 1995 | 7632740 |
| a novel expression vector composed of a regulatory element of the human leukosialin-encoding gene in different types of mammalian cells. | the regulatory element (re) of the human leukosialin (ls)-encoding gene, that encodes a major sialoglycoprotein of human leukocyte and platelet membranes, was used to develop a novel expression vector, pkx. the vector was constructed by cloning a re fragment and the sv40 fragment containing polyadenylation and splicing signals between hindiii and bamhi sites of the pcat-basic vector. the transcription level controlled by this vector was evaluated in six different cell lines using a transient exp ... | 1995 | 7642111 |
| expression of the mouse mammary tumor virus long terminal repeat open reading frame promotes tumorigenic potential of hyperplastic mouse mammary epithelial cells. | the retrovirus mouse mammary tumor virus (mmtv) 3' long terminal repeat (ltr) contains an open reading frame (orf) for a 36-kda protein and encodes a superantigen activity [porf(sag)]. we have tested the potential oncogenic activity of porf(sag) in two immortalized mouse mammary epithelial cells. we subcloned mmtv ltr orf dna into the prc/cmv mammalian expression vector in order to place ltr orf transcription under the control of the constitutive cmv promoter. mouse mammary epithelial cell lines ... | 1995 | 7645239 |
| dietary effects on gene expression in mammary tumorigenesis. | studies were undertaken to determine the effect a high fat diet has on the hormonally controlled transcription of the mtv-1 locus in c3hf mice. the expression of this locus in the initiating event in mammary tumor development in the c3hf mouse. mice were weaned at 21 days to either a high fat diet containing 23.5 percent corn oil or to a low fat diet containing 5 percent corn oil. mice were sacrificed at first, second, and third parity, or when they had developed mammary tumors, and their mammar ... | 1995 | 7645430 |
| intracellular expression of the monoclonal anti-ras antibody y13-259 blocks the transforming activity of ras oncogenes. | microinjection of the anti-ras antibody mab y13-259 modifies ras function and can induce temporary reversion of the transformed phenotype in mutant ras-transformed cells. intracellular production of neutralizing antibodies represents an approach to investigate the regulation of gene function. the genes coding for the heavy and light chains of mab y13-259 were isolated from a cdna library. nih3t3 cells transfected with heavy and light chain expression vectors produced functional anti-ras antibody ... | 1995 | 7647040 |
| glucocorticoid-mediated immunomodulation: hydrocortisone enhances immunosuppressive endogenous retroviral protein (p15e) expression in mouse immune cells. | to define glucocorticoid (gc)-regulated genes contributing to the anti-inflammatory and immunosuppressive effects of gc, previous work from our laboratory revealed up-regulation of transcripts from endogenous type b mouse mammary tumour virus (mtv) and type c murine leukaemia virus (emv) loci by high dose gc treatment of p388d1 macrophage-like cells. this study demonstrates enhancement of expression from mtv and emv loci in p388d1 cells by more physiological hydrocortisone concentrations (1 micr ... | 1995 | 7648710 |
| nucleosome positioning on the mmtv ltr results from the frequency-biased occupancy of multiple frames. | the translational positions of nucleosomes in the promoter region of the mouse mammary tumor virus (mmtv) were defined at high resolution. nucleosome boundaries were determined in primer extension assays using full-length single-stranded mononucleosomal dna prepared from cells treated with formaldehyde, a reversible protein-dna cross-linking agent. multiple boundaries were observed in both the nucleosome a (nuc-a) and nuc-b region of the promoter, indicating multiple nucleosome translational fra ... | 1995 | 7649476 |
| androgen receptor antagonist versus agonist activities of the fungicide vinclozolin relative to hydroxyflutamide. | the mechanism of antiandrogenic activity of vinclozolin (3-(3,5-dichlorophenyl)-5-methyl-5-vinyloxazolidine-2,4-dione), a dicarboximide fungicide under investigation for its potential adverse effects on human male reproduction, was investigated using recombinant human androgen receptor (ar). the two primary metabolites of vinclozolin in plants and mammals are m1 (2-[[3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid) and m2 (3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide). both metab ... | 1995 | 7650017 |
| conditional immortalization of primary cells by human papillomavirus type 18 e6 and ej-ras defines an e6 activity in g0/g1 phase which can be substituted for mutations in p53. | the human papillomavirus (hpv) type 18 e6 gene cooperates with activated ha-ras to immortalize primary mouse cells in culture. using a plasmid where hpv18 e6 expression is regulated by the glucocorticoid inducible mmtv ltr, we have generated immortalized cell lines in which the continued expression of e6 was necessary for maintenance of the transformed phenotype. in the absence of exogenously added hormone these cells were found to arrest in g0/g1. furthermore, we demonstrate that the effects of ... | 1995 | 7651728 |
| transfer of endogenous retroviral superantigen from donor to recipient b cells following priming to induce peripheral t cell tolerance. | endogenous retroviral superantigens such as vsag-7 are highly stimulatory for t cells through interaction with the t cell receptor on the basis of v beta usage. priming of adult mmtv 7-negative mice with vsag-7-expressing cells has been shown to result in peripheral v beta 6/cd4+ t cell activation followed by tolerance to further interaction with the superantigen. the goal of the current study was to examine the cells presenting vsag-7 during this initial burst of in vivo t cell activation. prim ... | 1995 | 7656330 |
| [humoral antibodies to structural proteins of murine mammary tumor virus as a potential immunologic marker of human breast cancer]. | the presence of humoral antibodies specifically recognizing structural proteins of murine mammary tumor virus was studied in indirect immuno-enzymatic reaction, in 79 patients with suspected tumors of the breast. diagnosis was verified after surgery by histological procedures. said antibodies were detected in 13% of patients with benign tumors, lymphomas and mammary lymphosarcomas. however, in the breast cancer group including patients with t1-2n0m0 and t1n1m0, antibodies were identified in 85.7 ... | 1995 | 7667940 |
| in vitro inhibition of 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced activity by alpha-naphthoflavone and 6-methyl-1,3,8-trichlorodibenzofuran using an aryl hydrocarbon (ah)-responsive construct. | rat hepatoma h4iie and mouse hepatoma hepa 1c1c7 cells were transiently transfected with a plasmid construct that contained the bacterial chloramphenicol acetyltransferase (cat) gene under the control of the mouse mammary tumor virus promoter and one copy of the dioxin responsive element. treatment of transfected h4iie and hepa 1c1c7 cells with 10(-13) to 10(-6) m 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) resulted in a concentration-dependent increase in transient cat activity. maximum cat acti ... | 1995 | 7669069 |
| synergistic interaction of transforming growth factor alpha and c-myc in mouse mammary and salivary gland tumorigenesis. | the c-myc oncogene is commonly amplified in breast cancer and is known to interact synergistically with transforming growth factor alpha (tgf alpha) in vitro to promote phenotypic transformation of mammary epithelial cells. in addition, both genes are under sex steroid hormone regulation in breast cancer. we have used a bitransgenic mouse approach to test the relevance of myc-tgf alpha interaction in mammary gland tumorigenesis of virgin animals in vivo. we mated single transgenic tgf alpha and ... | 1995 | 7669729 |
| synergism between androgens and protein kinase-c on androgen-regulated gene expression. | androgen (r1881) induced transcriptional activity of the human androgen receptor, stably expressed in cho cells, can be stimulated an extra 2-fold by the addition of the protein kinase c activator, 4 beta-phorbol 12-myristate 13-acetate (pma). this extra stimulation is not observed when the protein kinase a activator bromoadenosine 3':5'-cyclic monophosphate (8-brcamp) is used. the transcriptional activity was measured using a reporter plasmid containing the mmtv-promoter, coupled to the lucifer ... | 1995 | 7672438 |
| mouse mammary tumor virus with rearranged long terminal repeats causes murine lymphomas. | mouse mammary tumor virus (mmtv) is a slowly transforming retrovirus associated primarily with the induction of mammary tumors. it is widely accepted that t-cell lymphomas of various mouse strains are associated with extra proviruses of mmtv. these extra proviruses showed site-specific rearrangements in the u3 region of long terminal repeats (ltrs), consisting of about 400 nucleotide deletions and occasional substitution resulting in unique tandem repeats. however, the question of whether these ... | 1993 | 7677952 |
| benign prostatic hyperplasia in a transgenic mouse: a new hormonally sensitive investigatory model. | recent advances in molecular biology have enabled incorporation of proto-oncogenes into the mouse germline. in this study we use a transgenic mouse line that overexpresses the fibroblastic growth factor (fgf) family member, int-2, under the control of mouse mammary tumor virus (mmtv) regulatory elements. one of the tissues targeted by mmtv is the mouse prostate. expression of the mmtv-int-2 transgene in male transgenic mouse carriers results in a dramatic enlargement of the prostate gland which ... | 1993 | 7679760 |
| potentiation of glucocorticoid receptor-mediated gene expression by the immunophilin ligands fk506 and rapamycin. | it has recently been discovered that the steroid receptor-associated heat shock protein, hsp56, belongs to the fk506 family of immunophilin proteins. the ability of hsp56 to bind the immunosuppressive macrolide fk506 has led to the speculation that the steroid receptor and immunophilin signal transduction pathways are functionally interrelated. we have tested this idea by assessing the effects of fk506 on glucocorticoid receptor (gr)-mediated expression of the murine mammary tumor virus-chloramp ... | 1993 | 7681058 |
| a mutation of the glucocorticoid receptor in primary cortisol resistance. | the precise molecular abnormalities that cause primary cortisol resistance have not been completely described. in a subject with primary cortisol resistance we have observed glucocorticoid receptors (hgr) with a decreased affinity for dexamethasone. we hypothesize that a mutation of the hgr glucocorticoid-binding domain is the cause of cortisol resistance. total rna isolated from the index subject's mononuclear leukocytes was used to produce first strand hgr cdnas, and the entire hgr cdna was am ... | 1993 | 7683692 |
| identification of a novel glucocorticoid response element within the genome of the human immunodeficiency virus type 1. | we have shown that (hiv-1) replication can be regulated by interaction between glucocorticoid hormones and the viral genome; treatment of acutely infected lymphoid and monocytoid cell lines with cortisol and dexamethasone increased hiv-1 production in culture. the magnitude of this response correlated with glucocorticoid receptor (gr) and gr message in responder and non-responder cell lines. furthermore, treatment of each of two hiv-infected cell lines with glucocorticoids led to enhancement of ... | 1993 | 7684876 |
| specific binding of progesterone receptor to progesterone-responsive elements does not require prior dimerization. | steroid-hormone receptors undergo, prior to binding to dna, a hormone-dependent dimerization. it is generally accepted that this dimerization is indispensable for the high-affinity binding of hormone receptor to hormone-responsive elements. using a progesterone-receptor mutant with the complete steroid-binding domain deleted (positions 663-930), with or without the epitope required for binding the monoclonal antibody let 126, we have shown that this receptor species was unable to undergo dimeriz ... | 1993 | 7685278 |
| direct evidence for the role of cooh terminus of mouse mammary tumor virus superantigen in determining t cell receptor v beta specificity. | it has recently been shown that open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses encode superantigens. these viral superantigens (vsags) stimulate most t cells expressing appropriate v beta s almost regardless of the rest of the variable components of the t cell receptors (tcr) expressed by those cells. vsags produce a type ii integral membrane protein with a nonessential short cytoplasmic domain and a large glycosylated extracellular cooh-terminal domain, which ... | 1993 | 7688034 |
| new superantigen specificity created by two amino acid replacements. | | 1993 | 7688349 |
| production and characterization of polyclonal antibodies against awnt-1, the axolotl homologue of the proto-oncogene product wnt-1. | the proto-oncogene wnt-1 (int-1) is activated by mouse mammary tumor virus retroviral insertion and contributes to the formation of mammary gland tumors in mice. during early development, it is expressed in small groups of cells in the developing central nervous system of fish, amphibians and mice. in the ambystoma mexicanum (axolotl) embryo, the expression profile of wnt-1 is biphasic. we have raised polyclonal antibodies against a synthetic peptide corresponding to a surface-exposed epitope of ... | 1993 | 7691335 |
| superantigens and their role in immune-mediated disease. | | 1993 | 7691970 |
| characterization of novel reverse transcriptase encoding human endogenous retroviral sequences similar to type a and type b retroviruses: differential transcription in normal human tissues. | the polymerase chain reaction was used to amplify genomic dna and reverse-transcribed rna from human lymphocytes, using primers derived from conserved regions within the retroviral reverse transcriptase. sequencing of 33 cloned amplification products revealed that a variety of sequences with similarity to mouse mammary tumor virus, mouse intracisternal a particle, and human endogenous retrovirus k10 were detected with this primer pair. the sequences were divided into six subgroups, with a nucleo ... | 1993 | 7692084 |
| pea3 is overexpressed in mouse metastatic mammary adenocarcinomas. | transgenic mice bearing the rat neu proto-oncogene under the transcriptional control of the mouse mammary tumor virus (mmtv) promoter develop focal mammary adenocarcinomas after long latency that are metastatic to the lung in a high percentage of the tumor-bearing animals. because expression of the neu gene in the mammary epithelium precedes the occurrence of tumors, it appears that another genetic event in addition to neu transgene expression is required for tumorigenesis. we have investigated ... | 1993 | 7692372 |
| tcrb-v12-specific superantigens encoded by mouse mammary tumor proviruses. | | 1994 | 7693584 |
| modulation of cell signaling pathways can enhance or impair glucocorticoid-induced gene expression without altering the state of receptor phosphorylation. | we have stably introduced expression vectors for the glucocorticoid receptor and a sensitive, hormone-responsive reporter (mouse mammary tumor virus-luciferase) into a human breast carcinoma-derived cell line. employing this cell line, we have conducted a detailed examination of the induction of glucocorticoid-regulated genes and the phosphorylation of glucocorticoid receptor following pharmacologic manipulation of cell signaling pathways. the hormone response can be enhanced from 2 to 10-fold b ... | 1993 | 7693681 |
| homologous down-regulation of the glucocorticoid receptor down-modulates cellular hormone responsiveness in human histiocytic lymphoma u937 cells. | one of the determinants of cellular responsiveness to glucocorticoid hormone is the concentration of the receptor protein. it is well-known that cellular receptor levels are down-regulated by the cognate ligands, but the biological significance of this homologous down-regulation of the receptor has not yet been completely understood. we showed that in human histiocytic lymphoma cell line u937 the cellular glucorticoid receptor was homologously down-regulated by means of both ligand binding and w ... | 1994 | 7704085 |
| t cell receptor v beta repertoire in mice lacking endogenous mouse mammary tumor provirus. | when endogenous mouse mammary tumor virus (mmtv) superantigens (sag) are expressed in the first weeks of life an efficient thymic deletion of t cells expressing mmtv sag-reactive t cell receptor (tcr) v beta segments is observed. as most inbred mouse strains and wild mice contain integrated mmtv dna, knowing the precise extent of mmtv influence on t cell development is required in order to study t cell immunobiology in the mouse. in this report, backcross breeding between balb.d2 (mtv-6, -7, -8 ... | 1995 | 7705418 |
| negative-acting factor and superantigen are separable activities of the mouse mammary tumor virus long terminal repeat. | the open reading frame contained within the long terminal repeat (ltr) of mouse mammary tumor virus encodes naf, a negative regulator of transcription, as well as a superantigen activity, sag, which causes the deletion of specific classes of t cells. in the present study, the effect of naf expression on different promoters and the coding requirements for naf and sag have been investigated. sag activity was found to require only sequences in the ltr, whereas sequences located within the gag gene ... | 1995 | 7708717 |
| superantigens and their role in infectious disease. | although the exact mechanisms by which superantigens may contribute to the pathogenesis of diseases are unknown, it seems increasingly likely that they have a role in the induction and pathogenesis of disease. the studies described here demonstrate that in several different diseases either bacterial or viral superantigens can be isolated from patients. there is also a preferential expansion of particular v beta t-cell subsets, which is a common feature of superantigen stimulation. from the work ... | 1995 | 7718212 |
| biology of mouse mammary tumor virus (mmtv). | mouse mammary tumor viruses (mmtv) replicate in the mammary gland, appear as infectious particles in mother's milk and invade the sucking pups from the intestinal tract. the immune system is essential for mmtv in the gut to reach the mammary gland. these properties make the life cycle of mmtv unique. we review the oncologically and immunologically intriguing events caused by mmtv in relation to the life cycle of the virus. | 1995 | 7720040 |
| amplification of chromosome band 11q13 and a role for cyclin d1 in human breast cancer. | in this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of dna on human chromosome 11 band q13. this amplification occurs in approximately 15% of primary breast cancers. several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin d1 in tumorigenesis. immunohistochemical staining indicates that cyclin d1 is expressed at ele ... | 1995 | 7720042 |
| modulation of androgen receptor transcriptional activity by the estrogen receptor. | estrogen/androgen receptor interactions in naturally occurring physiological systems and the effect of their respective steroid hormones on transcriptional activity remain undefined. in an attempt to delineate further the nature of the interaction between these two steroid hormone receptors we have examined the effect of cotransfection of androgen (ar) and estrogen receptor (er) cdnas on the expression of the mouse mammary tumor virus long terminal repeat region (mmtv-ltr) linked to the chloramp ... | 1994 | 7721655 |
| susceptibility to tumors induced by polyoma virus is conferred by an endogenous mouse mammary tumor virus superantigen. | a dominant gene carried in certain inbred mouse strains confers susceptibility to tumors induced by polyoma virus. this gene, designated pyvs, was defined in crosses between the highly susceptible c3h/bida strain and the highly resistant but h-2k-identical c57br/cdj strain. the resistance of c57br/cdj mice is overcome by irradiation, indicating an immunological basis. in f1 x c57br/cdj backcross mice, tumor susceptibility cosegregates with mtv-7, a mouse mammary tumor provirus carried by the c3h ... | 1995 | 7722447 |
| proteolytic processing is required for viral superantigen activity. | the mouse mammary tumor virus-7 superantigen (vsag7) is proteolytically processed in b cells at as many as three positions. proteolytic processing appears to be important for superantigen activity because a processed form of vsag7 was predominant among those forms that were found to bind to major histocompatibility complex class ii molecules. to determine the functional significance of proteolytic processing, a mutation was introduced in vsag7 at one of the sites where proteolytic cleavage is th ... | 1995 | 7722465 |
| the structure of an rna pseudoknot that causes efficient frameshifting in mouse mammary tumor virus. | the structure of a 34-nucleotide rna pseudoknot that causes efficient -1 frameshifting in the messenger rna of mouse mammary tumor virus has been investigated by nmr. spectral assignment of the pseudoknot was facilitated by comparative nmr studies on the pseudoknot and on two smaller hairpin rnas, and by using selective 13c labeling and 13c-edited nmr techniques. the three-dimensional structure of the pseudoknot has been determined. the frameshifter pseudoknot possesses structural features not o ... | 1995 | 7723043 |
| multi-strand binding of nuclear factors to a repressor of mouse mammary tumor virus transcription can be distinguished kinetically. | nre1 is a dna sequence element in the long terminal repeat of mouse mammary tumor virus that represses viral transcription in mature t cells. in addition to double-stranded binding activity, factors in jurkat t cell nuclear extracts bind specifically to each of the two single-strands of nre1. here we show that binding to the three forms of nre1 can be distinguished kinetically. the on rates for double, upper and lower-strand nre1 binding were 1.5, 3, and 11 min, respectively. binding was extreme ... | 1995 | 7726860 |
| bispecific antibodies retarget murine t cell cytotoxicity against syngeneic breast cancer in vitro and in vivo. | bispecific antibodies with specificity for cd3 and a tumor antigen can redirect cytolytic t cells to kill tumor targets, regardless of their natural specificity. to assess the clinical potential of bispecific antibodies for treatment of human cancers we have, in the present study, adapted a totally synergeic mouse model to the targeting of mouse t cells against mouse tumors in immunocompetent mice. we show that gp52 of the mouse mammary tumor virus (mtv) can serve as a tumor-specific antigen for ... | 1995 | 7728777 |
| hormone induces binding of receptors and transcription factors to a rearranged nucleosome on the mmtv promoter in vivo. | hormonal induction of the mouse mammary tumour virus (mmtv) promoter is mediated by interactions between hormone receptors and other transcription factors bound to a complex array of sites. previous results suggested that access to these sites is modulated by their precise organization into a positioned regulatory nucleosome. using genomic footprinting, we show that mmtv promoter dna is rotationally phased in intact cells containing either episomal or chromosomally integrated proviral fragments. ... | 1995 | 7737125 |
| the function of inducible promoter systems in f9 embryonal carcinoma cells. | embryonal carcinoma (ec) cells represent an important model for studying the regulation of cellular differentiation during embryonic development and tumor formation. the differentiation of ec cells is associated with changes in the expression of a number of cellular genes, some of which have been implicated directly in the regulation of differentiation. to facilitate further studies of the possible roles of cellular gene products during the differentiation of ec cells, we have used transient tra ... | 1995 | 7737354 |
| tissue-specific and ubiquitous factors binding next to the glucocorticoid receptor modulate transcription from the mouse mammary tumor virus promoter. | steroid hormones complexed with their receptors play an essential role in the regulation of mouse mammary tumor virus (mmtv) transcription. however, the need for additional tissue-specific regulatory factors is suggested by the lack of virus expression in liver, in which glucocorticoid receptors are highly abundant, and by the tissue-specific transcription of reporter genes linked to an mmtv long terminal repeat in transgenic mice. in this study, we characterized two distal-region regulatory ele ... | 1995 | 7745724 |
| mediation of glucocorticoid receptor function by transforming growth factor beta i expression in human pc-3 prostate cancer cells. | we investigated the role of glucocorticoids in controlling the proliferation of androgen-independent pc-3 human prostate cancer cells via the action of transforming growth factor beta 1 (tgf beta 1). the presence of glucocorticoid receptor (gr) in pc-3 cells was detected by immunoblotting analysis using a rabbit anti-gr polyclonal antibody against the synthetic human gr peptide (hgr383-393). in pc-3 cells, gr bound radiolabeled dexamethasone with an affinity similar to wild-type gr. in addition, ... | 1995 | 7753711 |