| mhc class ii limits the functional expression of endogenous superantigens in b cells. | the open reading frames of the 3' long terminal repeat of mouse mammary tumor viruses (mmtv) encode superantigens. when expressed with mhc class ii molecules on the surface of b cells, superantigens stimulate t cells expressing receptors with particular v beta elements. by using b cell lymphomas as model systems, we demonstrate that stimuli, including certain lymphokines (il-2 and il-5) and lps, that lead to increased mmtv transcript levels in b cells did not increase functional superantigen pre ... | 1993 | 8380190 |
| steroid hormone dependent changes in dna methylation and its significance for the activation or silencing of specific genes. | | 1993 | 8380354 |
| regulation of expression of mouse mammary tumor virus through sequences located in the hormone response element: involvement of cell-cell contact and a negative regulatory factor. | mouse mammary tumor virus (mmtv) is a latently oncogenic retrovirus responsible for the neoplastic transformation of mammary epithelial cells. its expression is regulated by steroids, polypeptide growth factors, and cell-type-specific factors. using gr mouse mammary cells and nih 3t3 fibroblasts stably transfected with chimeric constructs of the long terminal repeat region of mmtv, we have demonstrated a novel mechanism of cell-type-specific expression of this virus. in confluent monolayer cultu ... | 1993 | 8380466 |
| t-cell receptor b-v repertoire expression in the absence of an endogenous mouse mammary tumor provirus. | | 1993 | 8380566 |
| the glucocorticoid receptor and a putative repressor protein coordinately modulate glucocorticoid responsiveness of the mouse mammary tumor virus promoter in the rat hepatoma cell line m1.19. | signal transduction by glucocorticoid hormones is mediated by the intracellular glucocorticoid receptor protein. the mechanisms determining cell type- or tissue-specific differences in hormone responsiveness remain, however, unclear. to address this issue we have used two different rat hepatoma cell lines, 762 and 6.10.2, respectively, in which mouse mammary tumor virus has been stably integrated. nuclear extracts from both of these cell lines contained a factor that bound to a sequence motif ex ... | 1993 | 8380580 |
| mouse mammary tumor virus infection accelerates mammary carcinogenesis in wnt-1 transgenic mice by insertional activation of int-2/fgf-3 and hst/fgf-4. | transgenic mice carrying the wnt-1 protooncogene modified for expression in mammary epithelial cells exhibit hyperplastic mammary glands and stochastically develop mammary carcinomas, suggesting that additional events are necessary for tumorigenesis. to induce such events and to identify the genes involved, we have infected wnt-1 transgenic mice with mouse mammary tumor virus (mmtv), intending to insertionally activate, and thereby molecularly tag, cooperating protooncogenes. infection of breedi ... | 1993 | 8380647 |
| production and characterization of an mls-1-specific monoclonal antibody. | superantigens (sags) represent a new class of antigens, characterized as t cell receptor (tcr) v beta-reactive elements. bacterial toxins constitute the major group of exogenous sags, while the mouse mammary tumor virus (mmtv)-encoded mls molecules represent the endogenous sags. mls-1 is the prototype of the latter sags, because it elicits a very potent t cell stimulatory response in vitro in unprimed t cells expressing the tcr v beta 6 or 8.1 chains. in vivo, mls-1 causes deletion of immature t ... | 1993 | 8381154 |
| major histocompatibility complex-specific recognition of mls-1 is mediated by multiple elements of the t cell receptor. | we have recently shown that recognition of the mouse mammary tumor virus 9-associated superantigen (vsag-9) by murine v beta 17+ t cells is strongly influenced by the major histocompatibility complex (mhc) class ii haplotype of the presenting cells, resulting in a form of mhc-restricted recognition. this finding was unexpected, because t cell recognition of another well-characterized retroviral superantigen, minor lymphocyte-stimulating antigen 1 (mls-1), had been shown to be independent of the ... | 1993 | 8381156 |
| a gene encoding the ligand for deletion of t cells bearing tcrv beta 6 and v beta 8.1 cosegregates with a new endogenous mouse mammary tumor virus. | | 1993 | 8381390 |
| trafficking of wild-type and an endoproteolytic-site mutant of the mouse mammary tumor virus glycoprotein. | we have utilized a mouse mammary tumor virus (mmtv) glycoprotein gene containing a mutation in the endoproteolytic cleavage site to investigate the biological significance of processing, the structural requirements for and the events involved in the proteolytic maturation of mmtv. using oligonucleotide-directed mutagenesis, the endoproteolytic cleavage site within the mmtv glycoprotein was mutated from arg-ala-lys-arg to arg-ala-asn-gln and both the wild-type and mutated genes were transfected a ... | 1993 | 8381404 |
| phylogenetic and structural analyses of mmtv ltr orf sequences of exogenous and endogenous origins. | the long terminal repeat (ltr) of mouse mammary tumor virus (mmtv) harbors an open reading frame (orf) that encodes a glycoprotein and is present in all exogenous and endogenous mmtv proviruses. the orf protein has been reported to interact with the immune system of mice to cause deletion of specific v beta-bearing subsets of t cells. twenty-two mmtv ltr orf sequences were analyzed. although highly conserved, the mmtv orf sequences are not identical, with approximately 35% of the total variation ... | 1993 | 8382394 |
| calories, parity, and prolactin influence mammary epithelial kinetics and differentiation and alter mouse mammary tumor risk. | reduced calorie intake (rci) suppresses mouse mammary tumor virus (mmtv) transcription and reduces mammary tumor (mt) incidence in c3h/ou mice. since efficient retroviral expression requires cell division, we investigated whether the suppression of mmtv and mt by rci reflects changes in mammary histogenesis and lowered epithelial kinetics. prolactin (prl) augments mmtv transcription. since prl levels may be lowered by rci, we evaluated whether lowered prl in ad libitum-fed mice alters mammary hi ... | 1993 | 8382558 |
| synergistic induction of apoptosis with glucocorticoids and 3',5'-cyclic adenosine monophosphate reveals agonist activity by ru 486. | glucocorticoids induce a programmed cell death in immature murine t cells through a process that has been named apoptosis. cyclic amp-dependent protein kinase (pka) activity contributes to this response but acts through an undefined mechanism. steroid-induced cytolysis can be completely blocked by the glucocorticoid antagonist ru 486, which inhibits the transformation of the glucocorticoid receptor (gr) into a fully activated transcription factor. however, the ability of camp to act synergistica ... | 1993 | 8383286 |
| glucocorticoid-regulated stability of a constitutively expressed mouse mammary tumor virus glycoprotein. | glucocorticoids regulate the transport and processing of mouse mammary tumor virus (mmtv) glycoproteins in viral-infected htc rat hepatoma cells. to begin to determine the role of cellular components involved in this steroid-mediated response, a constitutively expressed mmtv glycoprotein gene containing a mutation in the endoproteolytic cleavage site was used to simplify the viral maturation products. expression of the uncleavable mmtv glycoprotein gene in transfected htc rat hepatoma cells demo ... | 1993 | 8383289 |
| characterization of mammary plaques in ddd mice congenic for mtv-2 gene, ddd/1-mtv-2/mtv-2. | ddd/1 mice free from exogenous mouse mammary tumor virus (mmtv) do not develop any neoplastic mammary lesions. in gr mice, the expression of mtv-2, an endogenous proviral mmtv, leads to 100% incidence of mammary ductal hyperplasias and tumors. an mtv-2 congenic line, ddd/1-mtv-2/mtv-2, was established by introducing mtv-2 from gr into ddd/1 to elucidate its function. development of mammary plaques (mpq) characterized by ductal hyperplasias was investigated in 152 congenic females on day 17 to 19 ... | 1993 | 8383648 |
| tissue distribution of mtv-7-like exogenous retroviral transcripts and clonal deletion of v beta 6+ t cells in mls-1b balb/c mice. | we have previously described an mls-1a-like clonal deletion of mature cd4+ t cells which express v beta 6 and v beta 8.1 chains of the tcr in half of the mice of a balb/c, mls-1b colony (balb/c ic). this occurs in the absence of the mtv-7 provirus which is responsible for the clonal deletion in mls-1a mice. we developed a polymerase chain reaction assay in order to study the presence of retroviral transcripts homologous to the viral superantigen gene (vsag) of mtv-7 and mtv-6 in various tissues. ... | 1993 | 8383996 |
| development of a recombinant bovine leukemia virus vector for delivery of a synthetic bovine growth hormone-releasing factor gene into bovine cells. | continuous intravenous infusion of bovine growth hormone-releasing factor (bgrf) increases milk synthesis in dairy cattle by as much as 46%. we have begun to develop a system for delivery and expression of a synthetic bgrf gene in cultured bovine cells using the provirus of the bovine leukemia virus (blv). the gene encoding synthetic bgrf, constructed from eight overlapping oligonucleotides, was fused to the whey acidic protein promoter (wap) or the mouse mammary tumor virus promoter (mmtv). the ... | 1993 | 8385087 |
| relationship between defective mouse mammary tumor virus envelope glycoprotein synthesis and grp78 synthesis in glucocorticoid-treated mouse lymphoma cells. evidence for translational control of grp78 synthesis. | we have found that synthesis of the 78-kda glucose-regulated protein, grp78, was increased following glucocorticoid treatment of s49 and w7mg1 mouse lymphoma cell lines. these lines synthesized a 74-kda mouse mammary tumor virus envelope glycoprotein precursor, pr74, both constitutively and in response to glucocorticoid treatment. in these cell lines, nascent pr74 was not processed normally but was retained within the endoplasmic reticulum where it was bound stably by grp78. grp78 synthesis was ... | 1993 | 8385109 |
| positive regulation of trna gene expression by the mouse mammary tumor virus-long terminal repeat in vitro. | the mouse mammary tumor virus long terminal repeat (mmtv-ltr) participates in the control of gene expression by providing a series of important dna binding sites at which trans-acting factors interact. among these factors are the steroid receptor, nuclear factor i (nfi) and the tata box factor (tfiid). the binding of these proteins facilitates the assembly of a transcriptionally competent complex, that includes rna polymerase ii, and activates the expression of juxtaposed genes in cis. a particu ... | 1993 | 8385315 |
| wild-type adenovirus type 5 transforming genes function as transdominant suppressors of oncogenesis in mutant adenovirus type 5 transformed rat embryo fibroblast cells. | transformation of cloned rat embryo fibroblast (cref) cells with the host-range adenovirus type 5 (ad5) mutant, h5hr1, results in transformants with a fibroblastic morphology which displays a cold-sensitive transformation phenotype and oncogenic potential in both nude mice and syngeneic rats. in contrast, wild-type (wt) ad5 transformed cref cells are epithelioid in morphology, temperature independent for transformation, and nontumorigenic. the present studies were conducted to analyze the contri ... | 1993 | 8385576 |
| characterization of experimental allergic encephalomyelitis-susceptible, biozzi ab/h (h-2dq1) mice which express h-2anod: analysis of t-cell receptor expression and the detection of a deletion ligand encoded by mtv-7. | biozzi (h-2dq1) ab/h mice are marked not only by their high titre antibody responses following immunization with protein antigens but are also susceptible to experimental allergic encephalomyelitis (eae) induction. the t-cell receptor (tcr) repertoire in this recently characterized strain was analysed. biozzi ab/h mice were found to express the thy-1a, ly-1b, ly-2b and ly-5b alleles. serological typing of the tcr-v beta + peripheral t cells suggested that the ab/h mice belong to the tcr-v beta b ... | 1993 | 8386133 |
| transient promoter activity in primary rat mammary epithelial cells evaluated using particle bombardment gene transfer. | the relative strengths of several commonly used viral promoters in primary cultures of rat mammary epithelial cells were studied using a particle bombardment gene transfer method. nih 3t3 cells were also examined as a representative cell line. initially, the conditions necessary for efficient gene transfer using particle bombardment were determined. discharge voltage for particle bombardment was evaluated to maximize the levels of gene expression and cell viability. after transfection, transgene ... | 1993 | 8386156 |
| peripheral t cell activation and deletion induced by transfer of lymphocyte subsets expressing endogenous or exogenous mouse mammary tumor virus. | murine t cell reactivity with products of the minor lymphocyte stimulatory (mls) locus correlates with the expression of particular variable (v) domains of the t cell receptor (tcr) beta chain. it was recently demonstrated that mls antigens are encoded by an open reading frame (orf) in the 3' long terminal repeat of either endogenous or exogenous mouse mammary tumor virus (mmtv). immature thymocytes expressing reactive tcr-v beta domains are clonally deleted upon exposure to endogenous mtv's. ma ... | 1993 | 8386743 |
| distinct amounts of polyomavirus large t antigen are required for different functions of the protein. | many cellular and some virally coded proteins regulating key events in higher cells have been found to be multifunctional. one example of such a protein is the polyomavirus large t antigen, which is involved not only in viral dna replication and gene expression but also in the induction of the s phase in host cells, in the immortalization of various cell types and in the transactivation of some cellular genes. we recently constructed cell lines in which t antigen was synthesized under the contro ... | 1993 | 8386826 |
| activation of both wnt-1 and fgf-3 by insertion of mouse mammary tumor virus downstream in the reverse orientation: a reappraisal of the enhancer insertion model. | in retrovirus-induced tumors, proviral dna is commonly found next to or within a cellular proto-oncogene such that transcription of the gene is influenced by the viral promoter or enhancer. extensive surveys of naturally occurring tumors reveal that proviruses integrated on the 3' side of the gene are usually in the same transcriptional orientation, suggesting a model in which the bidirectional viral enhancer acts primarily on the closest promoters. here we describe a virally induced mammary tum ... | 1993 | 8386870 |
| mls-1 superantigen: molecular characterization and functional analysis. | | 1993 | 8387454 |
| influence of viral superantigens on v beta- and v alpha-specific positive and negative selection. | in mice, v beta-specific negative selection is mediated by a number of superantigens encoded by various mouse mammary tumor viruses. we have identified mtv-3, mtv-27, mtv-44, mtv-8, mtv-9, mtv-11, and mmtv(d2.gd), and have confirmed mtv-1. although specificities of superantigens correlate well with sequences of their carboxy terminal regions, mtv-44 appears to be an exception: the product is specific for v beta 3, v beta 6, v beta 8.1, and v beta 9. it remains to be determined whether mtv-44 pro ... | 1993 | 8387455 |
| exogenous and endogenous mouse mammary tumor virus superantigens. | | 1993 | 8387457 |
| the bacterial and mouse mammary tumor virus superantigens; two different families of proteins with the same functions. | in conclusion, the bacterial toxins are completely unlike the mtv superantigens in primary sequence and structure. the former are soluble globular proteins which do not have to be proteolytically cleaved before they act. the latter are synthesized as type ii membrane proteins and may be clipped before they reach the cell surface and act to stimulate t cells. table iii summarizes the similarities and differences between the two sets of superantigens. the most notable quality of these molecules is ... | 1993 | 8387458 |
| t-cell receptor repertoire selection by mouse mammary tumor viruses and mhc molecules. | | 1993 | 8387459 |
| t cell repertoire selection by mouse mammary tumour viruses. | mouse mammary tumour viruses (mtv) are b-type retroviruses. these can be exogenous, transmitted via maternal milk, or endogenous, as proviral integrations into the mouse genome, transmitted vertically in a mendelian fashion. a number of different sites of integration of endogenous mtvs have been reported in various inbred mouse strains. an open reading frame (orf), within the long terminal repeat (ltr) of mtv, encodes a type 2 integral membrane glycoprotein. the orf products are expressed in ass ... | 1993 | 8388249 |
| interaction of androgen and glucocorticoid receptor dna-binding domains with their response elements. | fusion proteins containing the glucocorticoid and the androgen receptor dna-binding domain (arf1 and grf1) were produced in escherichia coli. dnase i footprinting was used to compare the interaction of these proteins with responsive elements (res) in a typically glucocorticoid-responsive gene (mouse mammary tumour virus (mmtv)) and in an androgen-responsive gene (the c3(1) gene of rat prostatic binding protein). it is demonstrated that response elements which most closely resemble the consensus ... | 1993 | 8388338 |
| human t cells respond to mouse mammary tumor virus-encoded superantigen: v beta restriction and conserved evolutionary features. | mouse mammary tumor virus (mmtv)-encoded superantigens (sags) influence the murine t cell repertoire and stimulate a strong mixed lymphocyte response in vitro. these sags are encoded by the open reading frame of the 3' long terminal repeat of mmtv, termed mmtv sags. the t cell response to mmtv sags is v beta restricted and requires expression of the class ii molecules of the major histocompatibility complex (mhc) on the presenting cells. while human t cells respond to bacterial sags, it is not k ... | 1993 | 8388432 |
| the constitution of a progesterone response element. | progesterone receptors (prs) recognize and bind to dna in a sequence-specific manner. to define the sequence-specific determinants of pr binding to dna, we employed a detailed series of target elements and analyzed both pr binding in vitro and pr-mediated activation of a reporter gene in vivo. these elements represent point substitution or insertion mutants of a progesterone response element derived from the mouse mammary tumor virus (mmtv). substitution of a g for the first t in the 15-base pai ... | 1993 | 8388996 |
| cell-specific bifunctional role of jun oncogene family members on glucocorticoid receptor-dependent transcription. | interaction between protein kinase c (pkc)- and glucocorticoid receptor (gr)-mediated signaling is suggested by the ability of the pkc activating phorbol ester 12-o-tetradecanoylphorbol-13-acetate (tpa) to inhibit gr-dependent transcription of the mouse mammary tumor virus (mmtv) long terminal repeat (ltr). here we report that this interference is cell specific, as tpa augmented dexamethasone-induced transcriptional activation of the mmtv ltr in several t cell lines but was inhibitory in nih-3t3 ... | 1993 | 8388998 |
| characterization of the interaction of the human mineralocorticosteroid receptor with hormone response elements. | although the mineralocorticosteroid receptor (mr) belongs to the superfamily of hormone-dependent transcription factors, the molecular mechanism by which it regulates gene expression is poorly understood. binding of the mr to target gene promoters has never been characterized, and specific mineralocorticosteroid response elements (mres) remain to be identified. the human mr (hmr) was overexpressed in sf21 insect cells using the baculovirus system. the high degree of similarity between the glucoc ... | 1993 | 8389140 |
| histones, nucleosomes and transcription. | it is becoming increasingly clear that nucleosome structure is integrally involved in gene regulation. in particular, the study of inducible genes has shown that nucleosomes not only contribute to a repressed basal state, but can also be rearranged in response to induction. the mechanism of this process is just beginning to be elucidated, and genetic studies have implicated several proteins in the modulation of nucleosome structure. | 1993 | 8389216 |
| a new strain congenic for the mtv-7/mls-1 locus of mouse chromosome 1. | | 1993 | 8389322 |
| the progesterone antagonist ru486 acquires agonist activity upon stimulation of camp signaling pathways. | the protein kinase a stimulator camp can potentiate the ability of progestins to induce the transactivation function of the human progesterone receptor (hpr). we questioned in the present study whether camp could functionally cooperate with the progestin antagonist ru486. in t47d human breast cancer cells, ru486 behaves as a pure antagonist with respect to induction of the progesterone-responsive mouse mammary tumor virus chloramphenicol acetyltransferase (mmtv-cat) reporter gene. it fails to st ... | 1993 | 8389450 |
| the cytoplasmic raf oncogene induces a neuronal phenotype in pc12 cells: a potential role for cellular raf kinases in neuronal growth factor signal transduction. | the neuron-like differentiation of pc12 cells is induced by nerve growth factor (ngf) through stimulation of a membrane-bound protooncoprotein signaling pathway containing the ngf receptor trk, the tyrosine kinase src, and the gtp-binding protein ras. the raf-1 and b-raf protooncogenes encode cytoplasmic serine/threonine kinases that are stimulated by ngf in a ras-dependent manner. to investigate the possible roles of cytoplasmic raf kinases in eliciting neuronal differentiation, we have express ... | 1993 | 8389463 |
| linkage of superantigen-like stimulation of syngeneic t cells in a mouse model of follicular center b cell lymphoma to transcription of endogenous mammary tumor virus. | the mhc class ii i-a(s) positive b cell lymphomas reticulum cell sarcoma (rcs) that arise in > 90% of sjl mice by the age of 12 months have superantigen-like stimulating properties. in the present study, therefore, rcs cell lines were examined for abnormal expression of endogenous mouse mammary tumor virus (mmtv) proviruses. extraordinarily high expression of a 1.8 kb mrna hybridizing with the long terminal repeat (ltr) of mmtv was found in both primary lymphomas and in vitro rcs lines, but not ... | 1993 | 8389694 |
| simultaneous characterization of dna-binding proteins and their specific genomic dna target sites. | | 1993 | 8389970 |
| a steroid-inducible promoter for the controlled overexpression of cloned genes in eukaryotic cells. | previous studies have shown that members of the steroid receptor family of transcriptional regulators can function synergistically when bound to multiple arrays of specific dna binding sites known as hormone response elements, usually located upstream of target genes. we have constructed a mammalian expression vector containing a synthetic promoter composed of five high-affinity glucocorticoid response elements (termed gre5) placed upstream of the adenovirus 2 major late promoter "tata" region. ... | 1993 | 8390672 |
| conditional expression of wild-type topoisomerase ii complements a mutant enzyme in mammalian cells. | alterations in the amino acid composition, phosphorylation pattern, or intracellular levels of topoisomerase ii have been associated with resistance to antineoplastic agents whose effects are mediated through interactions with this enzyme. to develop a model system with which to investigate the determinants of topoisomerase ii sensitivity or resistance to antineoplastic agents that target this enzyme, a cdna encoding the wild-type drosophila melanogaster topoisomerase ii was ligated into a mamma ... | 1993 | 8390979 |
| nucleosomes modulate access of transcription factor to the mmtv promoter in vivo and in vitro. | | 1993 | 8391238 |
| breast cancer and t-cell-mediated immunity to proteins of the mouse mammary tumour virus (mmtv). | we have previously reported that breast cancer patients and some healthy subjects show positive t-cell-mediated immune responses to a semi-purified mouse mammary tumour viral pool (mmtv). we have now used western blotting to analyse the specificity of the response and to determine the target polypeptides. two types of t-cell response to the viral antigens were examined, proliferation and mif release, the latter implies a dth status in vivo where primed lymphocytes are involved. two viral fractio ... | 1993 | 8391340 |
| mouse mammary tumor virus associated antigens and superantigens--immuno-molecular correlates of neoplastic progression. | there is a large body of literature on immune reactivity to mouse mammary tumor virus (mmtv) during mammary tumor progression. it is a general consensus that mmtv is antigenic and elicits cell-mediated and humoral immune responses. in addition, activation of non-specific inflammatory cells has been observed in various mouse preneoplastic and neoplastic mammary lesions. how these non-conventionally activated inflammatory cells affect tumor progression is a subject of debate. the discovery of mmtv ... | 1993 | 8391342 |
| bacterial and retroviral superantigens share a common binding region on class ii mhc antigens. | staphylococcal enterotoxin a (sea), one of the most potent t-cell mitogens known, has been classified as a bacterial superantigen on the basis of ability to stimulate v beta-specific t-cell subsets. sea interacts with class ii major histocompatibility complex (mhc) antigens on antigen-presenting cells and the t-cell antigen receptor (tcr) on t cells, resulting in a ternary complex of mhc-sea-tcr. mls antigens are known to be products of mouse mammary tumour virus (mmtv), and it has been reported ... | 1993 | 8391645 |
| endogenous superantigen expression controlled by a novel promoter in the mmtv long terminal repeat. | endogenous superantigens are encoded by the open reading frame contained within the mouse mammary tumour virus long terminal repeat (mmtv ltr). superantigen expression results in t-cell proliferation and, during early ontogeny, t-cell deletion. here we identify a novel promoter located upstream of the previously described mmtv promoter. transcripts from this promoter initiate within the u3 region of the mmtv ltr and splice to the acceptor for endogenous superantigen coding region. the novel u3 p ... | 1993 | 8391646 |
| de-regulation of endogenous retrotransposons in mouse mammary carcinomas of diverse etiologies. | of the several families of endogenous retrovirus-like elements present in the mouse genome, only mouse mammary tumor virus has been analyzed for its role in mammary carcinogenesis. very little is known about the expression and activities of other retro-elements in normal and malignant mammary epithelium. we have begun investigating the possible involvement of the 3 retrotransposons, intracisternal a particles (iaps), murine-leukemia-virus-related (mulvr) elements, and vl30 sequences, in neoplast ... | 1993 | 8392034 |
| the glucocorticoid receptor hormone binding domain mediates transcriptional activation in vitro in the absence of ligand. | we show that recombinant rat glucocorticoid receptor (vvgr) expressed using vaccinia virus is indistinguishable from authentic gr with respect to dna and hormone binding. in the absence of hormone, vvgr is mainly found in the cytoplasm in a complex with heat shock protein 90. upon incubation with ligand, vvgr is released from this complex and translocated to the nucleus. thus, the ligand binding domain displays the known biochemical properties. however, in vitro, transcription from a synthetic p ... | 1993 | 8392705 |
| the use of a dna-binding domain replacement method for the detection of a potential tr3 orphan receptor response element in the mouse mammary tumor virus long terminal repeat. | tr3 orphan receptor is a human homologue of the mouse nur77, n10 and rat ngfi-b, tis1 genes which may represent an early response gene involved in the control of cell proliferation. we have studied potential target genes for tr3 orphan receptor using the dna-binding domain replacement method. we found that mouse mammary tumor virus long terminal repeat-linked chloramphenicol acetyltransferase expression can be activated in transfected cells by a chimeric androgen receptor/tr3 orphan receptor/and ... | 1993 | 8392847 |
| large scale production and purification of human retrovirus-like particles related to the mouse mammary tumor virus. | human retrovirus-like particles related to mouse mammary tumor virus (mmtv) are secreted in a steroid-dependent manner by the breast cancer cell line t47d. we report the successful large scale production and purification of these particles from culture supernatants of t47d cells and describe the experimental conditions established for this purpose. thus, mg amounts of particles were produced by large scale culturing of t47d cells in an autoharvesting roller bottle system and purified by differen ... | 1993 | 8393415 |
| the glucocorticoid receptor acts as an antirepressor in receptor-dependent in vitro transcription. | glucocorticoid-receptor-dependent and glucocorticoid-response-element-dependent in vitro transcription was established using a crude nuclear extract and purified glucocorticoid receptor from rat liver. the capacity of glucocorticoid receptor to stimulate in vitro transcription was only detectable when basal transcription, i.e. transcription in the absence of glucocorticoid receptor, had been repressed. transcriptional repression was achieved either by adding purified histone h1, or by lowering t ... | 1993 | 8393792 |
| mouse mammary-tumor virus activates fgf-3/int-2 less frequently in tumors from virgin than from parous mice. | tumorigenesis by mouse mammary-tumor virus (mmtv) involves proviral disruption and transcriptional activation of a number of cellular oncogenes, generically termed int. the frequencies with which different int genes are activated in different mouse strains can be quite variable, and previous surveys have suggested that insertions at int-2/fgf-3 occur primarily in strains that develop pregnancy-dependent mammary tumors. to address this issue, we have determined the relative contributions of 5 kno ... | 1993 | 8393839 |
| transgenic mouse models of mammary tumorigenesis. | | 1993 | 8394206 |
| superantigen-induced immune stimulation amplifies mouse mammary tumor virus infection and allows virus transmission. | endogenous and infectious mouse mammary tumor viruses (mmtvs) encode in their 3' long terminal repeat a protein that exerts superantigen activity; that is, it is able to interact with t cells via the variable domain of the t cell receptor (tcr) beta chain. we show here that transmission of an infectious mmtv is prevented when superantigen-reactive cells are absent through either clonal deletion due to the expression of an endogenous mtv with identical superantigen specificity or exclusion due to ... | 1993 | 8394220 |
| suppression of c-myc is a critical step in glucocorticoid-induced human leukemic cell lysis. | glucocorticoids evoke cytolysis in clonal human leukemic cem-c7 cells. suppression of c-myc mrna by dexamethasone closely correlates with cell lysis only in cem clones with both glucocorticoid receptor and intact lysis functions. we tested the theory that c-myc repression is essential for glucocorticoid-induced lymphocytolysis by preventing down-regulation of c-myc gene in the presence of dexamethasone and by reducing c-myc mrna levels with antisense oligonucleotides. we find that sustained expr ... | 1993 | 8394364 |
| the glucocorticoid receptor precludes the binding of a transcriptional repressor protein to the long terminal repeat of the mouse mammary tumor virus. | the long terminal repeat (ltr) of the mouse mammary tumor virus was used as a template to examine the dual binding parameters of the glucocorticoid-receptor (gr) and a repressor protein termed inhibitory factor 1 (if1). the receptor binds specifically to the glucocorticoid response element and precludes the binding of if1 to its juxtaposed binding site within the ltr. when the two dna targets are separated by the insertion of an additional 52 base pairs, coincident binding of both proteins is ob ... | 1993 | 8394505 |
| biological and endocrinological insights into the possible breast cancer risk from menopausal estrogen replacement therapy. | the question of whether estrogen therapy increases the risk of breast cancer is reviewed. despite more than 60 epidemiological studies and several meta-analyses over a five-decade period, there is no consensus about the answer. at present, the majority of investigators agree that short-term or medium-term therapy (less than 10 years) poses no measurable risk; some, but not all, investigators feel that there is a modest risk with long-term therapy (more than 15 years). even this semi-consensus is ... | 1993 | 8395097 |
| sequence similarity between the long terminal repeat coding regions of mammary-tumorigenic balb/cv and renal-tumorigenic c3h-k strains of mouse mammary tumor virus. | the long terminal repeat (ltr) of mouse mammary tumor virus (mmtv) encodes a protein which functions as a superantigen. the balb/cv strain differs from other exogenous mmtvs antigenically, biochemically, on the basis of restriction fragment analysis, and by the specificity of its superantigen for v beta 2+ t cells. in order to elucidate the origin of the balb/cv virus and to better understand the interaction of its superantigen with the t cell receptor, we have determined the nucleotide sequence ... | 1993 | 8395120 |
| presentation of the mls-1 superantigen by human hla class ii molecules to murine t cells. | superantigens (sag) presented in the context of mhc class ii proteins stimulate a strong proliferative response in t cells expressing particular tcr v beta genes. although this t-cell recognition is not mhc restricted, a strong hierarchy is observed in the ability of various mhc class ii molecules to present sag. mls-1, encoded by the murine mammary tumor virus (mmtv) mtv-7 sag gene, is the prototype of endogenous sag. in the present study, we have analyzed whether this retroviral gene product c ... | 1993 | 8395548 |
| latent agonist activity of the steroid antagonist, ru486, is unmasked in cells treated with activators of protein kinase a. | ru486 is a glucocorticoid and progesterone antagonist. in glucocorticoid-responsive fibroblasts, it mediates little or no induction of a truncated, hormone-responsive mouse mammary tumor virus promoter; moreover, it abrogates the induction mediated by the glucocorticoid agonist, dexamethasone. however, when the fibroblasts are treated with activators of protein kinase a, 8-br-camp or forskolin, along with ru486, the steroid now acts as a partial agonist, capable of mediating an induction of horm ... | 1993 | 8395651 |
| extraction of dna-binding proteins from cryogenically preserved cells. | we demonstrate that dna-binding protein extracts can be effectively prepared directly from tissue culture cells preserved under liquid nitrogen without returning the cells to culture. we prepared dna-binding protein extracts directly upon thawing of t47d, jurkat and cac-l153s cell lines after storage in liquid nitrogen for periods of up to one year. our results show that dna binding of a repressor of mouse mammary tumor virus transcription in these extracts is indistinguishable from binding acti ... | 1993 | 8395863 |
| glucocorticoid-regulated trafficking of mouse mammary tumor virus proteins in permeabilized hepatoma cells. requirements of intracellular membrane transport for maturation of the cytoplasmic phosphorylated polyprotein. | glucocorticoids coincidentally regulate the localization of mouse mammary tumor virus (mmtv) glycoproteins and maturation of viral phosphoproteins in viral infected rat hepatoma cells. to test for a functional interaction between mmtv transmembrane glycoproteins and cytoplasmic phosphoproteins, the bacterial cytolysin streptolysin-o was utilized to selectively permeabilize the plasma membrane and reconstitute exocytic trafficking. streptolysin-o-permeabilized m1.54 cells pretreated with glucocor ... | 1993 | 8396142 |
| expression of a mhc class ii transgene determines both superantigenicity and susceptibility to mammary tumor virus infection. | milk-borne mouse mammary tumor virus (mmtv) is a type b retrovirus that induces mammary carcinoma. infectious mmtv, as well as genomically integrated mouse mammary proviruses, encode superantigens that are recognized by t cells that express appropriate t cell receptor v beta products. to determine the relationship between the superantigenic property of milk-borne mmtv and its in vivo infectivity, mice which were either positive or negative for expression of a transgene-encoded e alpha e beta cla ... | 1993 | 8397273 |
| superantigens and their potential role in human disease. | in the past few years, there has been a virtual explosion of information on the viral and bacterial molecules now known as superantigens. some structures have been defined and the mechanism by which they interact with mhc class ii and the v beta region of the t cell receptor is being clarified. data are accumulating regarding the importance of virally encoded superantigens in infectivity, viral replication, and the life cycle of the virus. in the case of mmtv, evidence also suggests that superan ... | 1993 | 8397479 |
| theories of breast carcinogenesis. | | 1993 | 8397848 |
| role of the gene on trisomic and pentasomic chromosome 13 in murine mammary tumorigenesis. | to study a possible role(s) played by the trisomy and pentasomy of chromosome 13 in murine mammary tumors, we examined, in eight cloned established cell lines derived from a single balb/c mammary tumor induced by mtv, a correlation between the presence of trisomy or pentasomy 13 and transformation parameters and in vivo tumorigenicity in syngeneic mice. we found that cell lines with a higher incidence of trisomy or pentasomy 13 in cells of diploid and tetraploid chromosome numbers, respectively, ... | 1993 | 8402544 |
| nonspecific augmentation of lymph node t cells and i-e-independent selective deletion of v beta 14+ t cells by mtv-2 in the ddd mouse. | ddd/1 (ddd) mice were characterized by marked paucity of t cells in lymph nodes (ln). in ddd-mtv-2/mtv-2 (ddd-mtv-2) congenics, t cells were 4- to 18-fold increased depending on ages but b cells doubled at the most. thymus weight also increased. in dddfddd-mtv-2, ddd neonatally infected with mtv-2-derived exogenous mmtv (mmtv-2), neither ln cells nor thymus weight increased. the v beta 5+ and v beta 8+ t cell contents in ln were practically the same among three strains. the mtv-2-induced expansi ... | 1993 | 8405042 |
| site-directed mutagenesis of the phosphorylation sites in the mouse glucocorticoid receptor. | the functional significance of receptor phosphorylation in mediating the actions of glucocorticoids remains undefined. the identification of seven phosphorylation sites in the mouse glucocorticoid receptor (bodwell, j. e., orti, e., coull, j. m., pappin, d. j. c., smith, l. i., and swift, f. (1991) j. biol. chem. 266, 7549-7555) permits a direct examination of the potential regulatory role of glucocorticoid receptor phosphorylation in transactivation. using oligonucleotide-directed mutagenesis o ... | 1993 | 8407999 |
| the mouse mammary tumor virus long terminal repeat encodes a 47 kda glycoprotein with a short half-life in mammalian cells. | the mouse mammary tumor virus proviral dna contains an open reading frame in the 3' long terminal repeat which can code for a 36 kda polypeptide with a putative transmembrane sequence and five n-linked glycosylation sites. this gene is known to code for a superantigen which deletes a specific subset of cd4+ t lymphocytes in vivo. the superantigen encoded by the exogenous mouse mammary tumor virus of the gr strain acts specifically on v beta 14 bearing t cells. we produced recombinant vaccinia vi ... | 1993 | 8413319 |
| expression of an exogenous eukaryotic dna methyltransferase gene induces transformation of nih 3t3 cells. | abnormal regional increases in dna methylation, which have potential for causing gene inactivation and chromosomal instability, are consistently found in immortalized and tumorigenic cells. increased dna methyltransferase activity, which is also a characteristic of such cells, is a candidate to mediate these abnormal dna methylation patterns. we now show that, in nih 3t3 mouse fibroblasts, constitutive overexpression of an exogenous mouse dna methyltransferase gene results in a marked increase i ... | 1993 | 8415627 |
| relationship of levels and kinetics of h-ras expression to transformed phenotype and loss of tgf-beta 1-mediated growth regulation in intestinal epithelial cells. | immortalized, nontumorigenic rat intestinal epithelial cells (iec-18) can be transformed to tumorigenicity by expression of an activated human h-ras gene. here we describe the characteristics of an iec-18 cell line in which the activated human h-ras gene has been introduced under the control of the steroid-sensitive promoter of the mouse mammary tumor virus long-terminal repeat. the clonal cell line (iec-18 c125) is phenotypically normal in the absence of the transcription inducer, dexamethasone ... | 1993 | 8416798 |
| growth factor dependency and gene expression in preneoplastic mouse mammary epithelial cells. | the tm preneoplastic mammary outgrowth lines were established in vivo from mammary epithelial cell lines and have been characterized with respect to their tumorigenic, morphological, and functional properties. the tm outgrowth lines were then established as in vitro cell lines. a comparison of the growth factor dependencies of the tm preneoplastic lines and their progenitor cell lines grown in monolayer cell culture indicated that the tm preneoplastic cell lines exhibited a decreased dependence ... | 1993 | 8425201 |
| familial glucocorticoid resistance caused by a splice site deletion in the human glucocorticoid receptor gene. | the clinical syndrome of generalized, compensated glucocorticoid resistance is characterized by increased cortisol secretion without clinical evidence of hyper- or hypocortisolism, and manifestations of androgen and/or mineralocorticoid excess. this condition results from partial failure of the glucocorticoid receptor (gr) to modulate transcription of its target genes. we studied the molecular mechanisms of this syndrome in a dutch kindred, whose affected members had hypercortisolism and approxi ... | 1993 | 8445027 |
| characterization of two cis-acting dna elements involved in the androgen regulation of the probasin gene. | the location and sequence of androgen responsive elements (ares) in the 5'-flanking dna of the androgen-regulated rat probasin (pb) gene were determined. the dna- and steroid-binding domains of the rat androgen receptor [glutathione-s-transferase (gst)-ar1] and the dna-binding domain and hinge region alone (gst-ar2) were expressed in escherichia coli as isopropyl-b-d-thioglactopyranoside-induced fusion proteins with gst and purified using glutathione affinity chromatography. band shift assays in ... | 1993 | 8446105 |
| a link between ras and metastatic behavior of tumor cells: ras induces cd44 promoter activity and leads to low-level expression of metastasis-specific variants of cd44 in cref cells. | the activated oncogene c-ha-ras induces expression of the surface glycoprotein cd44 in cloned rat embryonic fibroblasts (cref). induction is transcriptional as shown by transient cotransfections of c-ha-ras expression constructs and cd44 promoter reporter gene constructs and depends on the presence of an ap-1 binding site at position -110. increased transcript levels for the standard isoform of cd44 (cd44s) are accompanied by the appearance of alternatively spliced rnas and the synthesis of vari ... | 1993 | 8453616 |
| do superantigens play a role in autoimmunity? | mycoplasma arthritidis produces a typical soluble superantigen (sag) which shares many characteristics with bacterial toxins and mouse mammary tumor virus sag. however, this microbe is associated with an autoimmune-like disorder and this disease may therefore serve as a model to investigate the potential role of a sag in autoimmune disease pathogenesis. | 1993 | 8467097 |
| aberrant expression of high mobility group chromosomal protein 14 affects cellular differentiation. | high mobility group (hmg) 14 is a ubiquitous chromosomal protein that binds specifically to nucleosomal dna and may be involved in a process that confers distinct properties to the chromatin structure of transcriptionally active genes. to explore the involvement of this protein in regulation of gene expression, we studied the effect of aberrant expression of hmg-14 protein on cellular differentiation. we produced stably transfected c2c12 mouse myoblasts expressing the human hmg-14 protein under ... | 1993 | 8514795 |
| production of minor lymphocyte stimulatory-1a antigens from t cell subsets. | t cell subsets that produce minor lymphocyte stimulatory (mls) antigens were analyzed using mixed lymphocyte reaction (mlr) in vitro or clonal elimination assay in vivo. when lymph node t cells from b10.br(mls-1b) mice were stimulated with various t cell subsets from akr (mls-1a) mice in the presence of b10.br antigen presenting cells (apc), proportions of mls-1a reactive t cell blasts (v beta 6+, v beta 8.1+) increased. the stimulatory potency of cd8+ t cells was higher than that of cd4+ t cell ... | 1995 | 8522355 |
| efficient dual transcomplementation of adenovirus e1 and e4 regions from a 293-derived cell line expressing a minimal e4 functional unit. | transgene expression after the administration of recombinant adenovirus with e1 deleted is constantly transient. it is admitted that e1a-substituting activities of cellular or viral origin allow viral antigen synthesis and trigger cytotoxic lymphocyte-mediated clearance of the recipient cells. our approach to solving this problem relies on the additional deletion of the e4 region from the vector backbone as this region upregulates viral gene expression at both transcriptional and posttranscripti ... | 1996 | 8523570 |
| inducible expression of ras n17 dominant inhibitory protein. | | 1995 | 8524106 |
| constitutive repression and nuclear factor i-dependent hormone activation of the mouse mammary tumor virus promoter in saccharomyces cerevisiae. | to study the influence of various transactivators and the role of nucleosomal structure in gene regulation by steroid hormones, we have introduced mouse mammary tumor virus (mmtv) promoter sequences along with expression vectors for the glucocorticoid receptor (gr) and nuclear factor i (nfi) in saccharomyces cerevisiae, an organism amenable to genetic manipulation. both in the context of an episomal multicopy vector and in a centromeric single-copy plasmid, the mmtv promoter was virtually silent ... | 1995 | 8524266 |
| localization, trafficking, and temperature-dependence of the aequorea green fluorescent protein in cultured vertebrate cells. | the localization, trafficking, and fluorescence of aequorea green fluorescent protein (gfp) in cultured vertebrate cells transiently transfected with gfp cdna were studied. fluorescence of gfp in uv light was found to be strongest when cells were incubated at 30 degrees c but was barely visible at an incubation temperature of 37 degrees c. cos-1 cells, primary chicken embryonic retina cells, and carp epithelial cells were fluorescently labeled under these conditions. gfp was distributed uniforml ... | 1995 | 8524871 |
| minimal signal requirements for superantigen-specific t cell-driven b cell proliferation. | | 1995 | 8525890 |
| unsaturated fatty acids synergistically enhance glucocorticoid-induced gene expression. | regulation by unsaturated fatty acids of glucocorticoid-sensitive gene transcription was studied in hela cells transiently transfected with a mouse mammary tumour virus-luciferase reporter gene. arachidonic acid and docosahexaenoic acid by themselves had no effect on basal levels of luciferase expression. however, they were able to enhance dexamethasone-induced transcription by 1.4-2.3 times (25-42 times the control levels) in a dose-dependent manner (ed50: 18 and 8 microm) for arachidonic and d ... | 1995 | 8527300 |
| a fraction enriched in a novel glucocorticoid receptor-interacting protein stimulates receptor-dependent transcription in vitro. | glucocorticoids influence numerous cell functions by regulating gene activity. the glucocorticoid receptor (gr) is a ligand-activated transcription factor and, like any other transcription factor, does not modulate gene activity just by binding to dna. interaction with other proteins is probably required to enhance the establishment of a functional transcription initiation complex. to identify such proteins, we analyzed the in vitro interaction of the glucocorticoid receptor bound to a double gl ... | 1995 | 8530516 |
| nuclear factor binding to a dna sequence element that represses mmtv transcription induces a structural transition and leads to the contact of single-stranded binding proteins with dna. | nre1 is a dna sequence element in the long terminal repeat of mouse mammary tumor virus through which viral transcription is repressed. in addition to double-stranded dna binding, both upper- and lower-stranded nre1 binding activities occur in nuclear extracts. all three binding activities appear to be important for transcriptional effects. we report that occupancy of nre1 within linear double-stranded nre1 induces a structural transition in upstream flanking dna that is facilitated by mg2+. thi ... | 1995 | 8534369 |
| partial androgen insensitivity caused by an androgen receptor mutation at amino acid 907 (gly-->arg) that results in decreased ligand binding affinity and reduced androgen receptor messenger ribonucleic acid levels. | androgen insensitivity is an x-linked disorder of sexual differentiation resulting from mutations in the androgen receptor (ar) gene. in this paper, we report the clinical phenotype and molecular analysis of two siblings with severe partial androgen insensitivity due to a novel mutation in the ligand-binding domain of the ar gene. binding studies using cultured genital skin fibroblasts demonstrated reduced ar affinity and binding capacity. nucleotide sequence analysis of the ar gene of both sibl ... | 1996 | 8550758 |
| major histocompatibility complex class ii i-e-independent transmission of c3h mouse mammary tumor virus. | c57bl/6 mice are resistant to c3h mouse mammary tumor virus (mmtv)-induced mammary tumorigenesis and lack major histocompatibility complex class ii i-e molecules that are essential for presentation of c3h superantigen to t cells. t cells are needed for transmission of milk-borne mmtv from the gut to the mammary gland. in this report, we show that infectious c3h mmtv is produced by c57bl/6 mice that nurse on c3h mothers but that virus production in the mammary gland is delayed compared with that ... | 1996 | 8551589 |
| int-2 influences the development of the nodose ganglion. | the int-2 gene was first described as a common proviral integration site in tumors induced by mouse mammary tumor virus (mmtv). during embryonic development int-2 is produced and released by cells in the rhombencephalon and diffuses to the ectoderm to induce formation of the otocyst from the otic placode. int-2 also influences the development of the vestibulocochlear ganglion that is derived from the otic placode. during embryogenesis the otic and nodose placodes, primordia of the inner ear and ... | 1995 | 8559598 |
| exogenous mouse mammary tumor virus (mmtv) infection induces endogenous mmtv sag expression. | the mouse mammary tumor virus (mmtv) superantigen (sag) protein is involved in the transmission of milk-borne mmtv from virus-infected milk in the gut to the target mammary gland tissue. using an rt-pcr assay for in vivo mmtv infection, balb/c or c3h mice nursed on c3h mmtv-infected mothers showed sag mrna expression in intestine, spleen, and thymus as early as 1 day after infection, whereas uninfected balb/c control animals had approximately 10- to 30-fold lower sag expression. further fraction ... | 1996 | 8560758 |
| molecular cloning of yeast cytochrome c-like polypeptide expressed in human lung carcinoma: an antigen recognizable by lung cancer-specific human monoclonal antibody. | we previously determined the amino acid sequence to the epitope (atlfktr) of cytochrome c from candida krusei, which is cross-reactive to the lung cancer-specific human monoclonal antibody hb4c5. here we report that an antigen messenger rna, which codes for a structure similar to the cytochrome c epitope, is expressed in the human lung adenocarcinoma a549. sequencing analysis has revealed that this messenger rna encodes a novel 190 amino acid polypeptide of 21-kda containing an amino acid sequen ... | 1995 | 8564085 |
| mutations involving the endogenous ecotropic murine leukemia virus in primary mammary carcinomas of balb/c mice. | endogenous murine leukemia virus-related elements (mlves) are often overexpressed in primary mammary carcinomas of balb/c mice. we therefore searched for mutations associated with mlves and found amplified sequences of the ecotropic mlve in hormonally and chemically induced mammary neoplasms. restriction fragment length polymorphism (rflp) analysis revealed dna rearrangements consistent with 1-10 or more new copies of the ecotropic mlve in the genome of these tumors. this is the first evidence o ... | 1996 | 8564923 |
| identification of a novel dexamethasone responsive enhancer in the human cyp3a5 gene and its activation in human and rat liver cells. | the human liver cytochromes p450 3a (cyp3as), orthologous to the rat glucocorticoid inducible forms, are composed of at least four differentially expressed members. to begin the study of the molecular events in the glucocorticoid regulation of cyp3a5, we fused 5' sequences of cyp3a5 to the chloramphenicol acetyltransferase gene in a vector that contains the herpes simplex virus thymidine kinase promoter. in hepg2 cells, the largest 5' cyp3a5 gene fragment (1.4 kb) suppressed the tk promoter. how ... | 1996 | 8569713 |
| ephemerally expressed wild-type and mutant steroid hormone receptors are equally able to influence expression of transient or resident templates. | we have tested transiently expressed mutant and chimeric glucocorticoid receptors (gr) for their ability to influence transcription of either a co-transfected or a stably integrated reporter gene. to the latter purpose we have generated a cell line harbouring 2 chromosomally anchored copies of the well-characterized mouse mammary tumor virus (mmtv) promoter/enhancer region fused to the bacterial beta-galactosidase gene (lacz). we were particularly interested in verifying whether some earlier cha ... | 1995 | 8574786 |
| nfi/x proteins: a class of nfi family of transcription factors with positive and negative regulatory domains. | nfi is a family of transcription factors that binds discrete nucleotide sequence and regulates transcriptional activity of genes. transactivation occurs through proline-rich sequences. among the genes whose transcriptional activity is regulated are those expressed in a cell-type specific manner. this suggests the possible existence of nfi proteins with distinct properties. with the use of the polymerase chain reaction technique, we have cloned and analyzed the activity of three spliced variants ... | 1995 | 8581067 |
| transcriptional control by steroid hormones: the role of chromatin. | the mouse mammary tumour virus (mmtv) promoter contains a complex hormone-responsive unit composed of four hormone-responsive elements, a nuclear factor i (nfi) binding site and two octamer motifs. all these sites are required for optimal hormonal induction. although synergism has been found between hormone receptors and octamer transcription factor 1 (oct-1/otf-1), we were unable to detect a positive interaction between receptors and nfi in vitro. in chromatin, the mmtv hormone-responsive unit ... | 1995 | 8582206 |
| receptors on t cells escaping superantigen-mediated deletion lack special beta-chain junctional region structural characteristics. | the tcr v beta element is pivotal for superantigen recognition; however, not all t cells bearing a particular v beta element respond to an individual superantigen. recent evidence has indicated that the tcr v alpha element also contributes to recognition of superantigen/mhc class ii complexes. to determine whether the tcr beta-chain junctional regions influence recognition of a superantigen encoded by mouse mammary tumor virus (mmtv) proviral integrant mtv-1, we have analyzed these regions in t ... | 1996 | 8596038 |