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At least 343 records · Page 19Linked to original sources
PubMed1990

Murine interleukin 2 receptor beta chain: dysregulated gene expression in lymphoma line EL-4 caused by a promoter insertion.

The functional, high-affinity interleukin 2 receptor (IL-2R) consists of at least two receptor components, IL-2R alpha (p55) and IL-2R beta (p70-75). The cDNA encoding the murine IL-2R beta has been isolated by using the previously cloned cDNA for human IL-2R beta as a probe. Analysis of the cDNA revealed that the murine IL-2R beta shows a marked homology with the human IL-2R beta and that it is also structurally related to other cytokine receptors such as erythropoietin receptor. The cDNA-directed murine IL-2R beta formed high-affinity IL-2R in conjunction with the endogenous IL-2R alpha in a murine pro-B-cell line and could transduce IL-2-induced growth signal. In mouse lymphoma line EL-4, the IL-2R beta gene was found to be rearranged by the insertion of the long terminal repeat sequence of an intracisternal A particle, giving rise to constitutive expression of the IL-2R beta mRNA.

Amino Acid Sequence↗
PubMed1991

Sexual transmission of human T-cell leukemia virus type I associated with the presence of anti-Tax antibody.

The tax gene product (Tax protein) of human T-cell leukemia virus type I (HTLV-I) is a specific transcriptional activator of the viral long terminal repeat sequence and is essential for the replication cycle of the virus. To elucidate the relationship between the presence of anti-Tax antibody and the transmission of the viral infection, annual consecutive serum samples from married couples serologically discordant or concordant for HTLV-I were examined. These included 5 individuals whose spouses seroconverted during this 5-year follow-up study period. The samples were tested by a Western blot assay using a recombinant Tax protein as the antigen. The results showed that 24 of 32 (75%) men in the concordant couples (both husband and wife were HTLV-I carriers) had anti-Tax antibody, while only 5 of 18 (27.8%) men in the discordant couples (husband was carrier and wife was seronegative to HTLV-I) were positive for anti-Tax antibody (P = 0.0012). Furthermore, all spouses of the 5 seroconverters (4 women and 1 man) had anti-Tax antibody, while only 23 of 46 (50%) age-matched randomly selected HTLV-I carriers from the discordant-couple group had anti-Tax antibody. When the data were analyzed by gender, all husbands of the female seroconverters had anti-Tax antibodies, which was significantly higher than the prevalence of anti-Tax antibodies in men who did not transmit the virus to their spouses during the follow-up period (P = 0.017). In addition, antibody reactivity to other HTLV-I antigens (including Env gp46, transmembrane protein gp21, and Gag p19 and p24) were examined. The results indicated no significant differences between the prevalence of antibody reactivity to any of the antigens in the spouses of the seroconverters and the reference group. We conclude that the presence of anti-Tax antibody in men may indicate a high risk of viral transmission to their wives via heterosexual routes.

Agglutination Tests↗
PubMed1997

Isoforms of ankyrin-3 that lack the NH2-terminal repeats associate with mouse macrophage lysosomes.

We have recently cloned and characterized ankyrin-3 (also called ankyrin(G)), a new ankyrin that is widely distributed, especially in epithelial tissues, muscle, and neuronal axons (Peters, L.L., K.M. John, F.M. Lu, E.M. Eicher, A. Higgins, M. Yialamas, L.C. Turtzo, A.J. Otsuka, and S.E. Lux. 1995. J. Cell Biol. 130: 313-330). Here we show that in mouse macrophages, ankyrin-3 is expressed exclusively as two small isoforms (120 and 100 kD) that lack the NH2-terminal repeats. Sequence analysis of isolated Ank3 cDNA clones, obtained by reverse transcription and amplification of mouse macrophage RNA (GenBank Nos. U89274 and U89275), reveals spectrin-binding and regulatory domains identical to those in kidney ankyrin-3 (GenBank No. L40631) preceded by a 29-amino acid segment of the membrane ("repeat") domain, beginning near the end of the last repeat. Antibodies specific for the regulatory and spectrin-binding domains of ankyrin-3 localize the protein to the surface of intracellular vesicles throughout the macrophage cytoplasm. It is not found on the plasma membrane. Also, epitope-tagged mouse macrophage ankyrin-3, transiently expressed in COS cells, associates with intracellular, not plasma, membranes. In contrast, ankyrin-1 (erythrocyte ankyrin, ankyrin(R)), which is also expressed in mouse macrophages, is located exclusively on the plasma membrane. The ankyrin-3-positive vesicles appear dark on phase-contrast microscopy. Two observations suggest that they are lysosomes. First, they are a late compartment in the endocytic pathway. They are only accessible to a fluorescent endocytic tracer (FITC-dextran) after a 24-h incubation, at which time all of the FITC-dextran-containing vesicles contain ankyrin-3 and vice versa. Second, the ankyrin-3-positive vesicles contain lysosomal-associated membrane glycoprotein (LAMP-1), a recognized lysosomal marker. This is the first evidence for the association of an ankyrin with lysosomes and is an example of two ankyrins present in the same cell that segregate to different locations.

Amino Acid Sequence↗
PubMed1992

A mutant tRNA affects delta-mediated transcription in Saccharomyces cerevisiae.

Mutations in the SPT3, SPT7, SPT8 and SPT15 genes define one class of trans-acting mutations that are strong suppressors of insertion mutations caused by Ty elements or by the Ty long terminal repeat sequence, delta. These SPT genes are required for normal transcription of Ty elements, and their gene products are believed to be involved in initiation of Ty transcription from delta sequences. We have isolated and analyzed extragenic suppressors of spt3 mutations. These new mutations, named rsp, partially suppress the requirement for SPT3, SPT7, SPT8 and SPT15 functions. In addition, rsp mutations cause changes in transcription of some delta insertions in an SPT+ genetic background. Interactions between mutations in the four identified RSP genes show a number of interesting genetic properties, including the failure of unlinked rsp mutations to complement for recessive phenotypes. Cloning and sequencing of one rsp mutant gene, rsp4-27, showed that it encodes a frameshift suppressor glycine tRNA. Our results indicate that the other three RSP genes also encode frameshift suppressor glycine tRNAs. In addition, other types of frameshift suppressor glycine tRNAs can confer some Rsp- phenotypes.

Alleles↗
PubMed1996

Endemic infection with human T cell leukemia/lymphoma virus type IIB in Argentinean and Paraguayan Indians: epidemiology and molecular characterization.

Human T cell leukemia/lymphoma virus (HTLV-II) type II infection was detected by polymerase chain reaction or serologic analyses (or both) in 22% of 697 Indians of six different ethnic back-grounds inhabiting the Argentinean and Paraguayan Gran Chaco. None was infected with HTLV-I. The prevalence of HTLV-II increased with age (14% in those < 13 years and 23% in those > or = 13 years). HTLV-II infection was found in all 20 Gran Chaco communities studied, but marked differences (44%-4%) in the rate of infection were observed even in communities separated by only a few miles. These variations correlated closely with ethnicity. In the high-incidence communities, infection clustered within families, with evidence for both sexual and perinatal transmission, primarily via breast-feeding. By contrast, only 2% of 94 Mapuche Indians from southern Argentina were positive for HTLV-II. Analyses of pol and long terminal repeat sequences from 15 Gran Chaco HTLV-II strains indicated that they constitute a highly conserved branch of the HTLV-IIB substrain.

Adolescent↗
PubMed1996

Immunoblastic lymphoma of donor origin in the allograft after lung transplantation.

Posttransplant lymphoproliferative disorders (PTLD) are EBV-associated lymphoid neoplasms that are caused by the uncontrolled growth of EBV-infected B lymphocytes. The clinical presentation of PTLD can range from benign polygonal lymphoproliferative disorders to aggressive monoclonal immunoblastic lymphomas. In this report, we describe a seronegative lung transplant recipient who developed an immunoblastic lymphoma 4 months after lung transplantation from a seropositive donor. The neoplastic cells expressed B lymphocyte markers (CD19+, CD20+, sIgM+, kappa+) as well as the EBV antigen EBNA-2. A cell line with similar cytologic features spontaneously grew from in vitro cultures of the patient's peripheral blood mononuclear cells. The cell line and the lymphoma were EBV+, expressed a similar spectrum of B cell surface proteins, and had the donor's HLA haplotype. Analysis of immunoglobulin gene rearrangements and viral terminal repeat sequences revealed that the cell line and the tumor represented distinct B cell clones. Cultured peripheral blood mononuclear cells were restimulated in vitro with the EBV transformed cell line and tested for cytolytic activity. The host T cells demonstrated high levels of cytolytic activity against the tumor cell line that was abrogated by the addition of a anti-monomorphic HLA class I monoclonal antibody (mAb) (W6/32). These studies indicate that cells of donor origin can persist in the transplanted organ and may lead to an EBV-associated posttransplant lymphoma.

Antibodies, Monoclonal↗
PubMed1996

Molecular epidemiology of HTLV-I in the world.

The geographic distribution of human T-cell lymphotropic/leukemia virus type I (HTLV-I) was initially believed to be limited to southwestern Japan, the Caribbean basin, and Africa. However, extensive searches in recent years have discovered its existence in other areas of the world as well as in isolated, ethnic populations such as South Amerindians, Australo-Melanesian aborigines, religiously segregated Jews, and Pygmies. Previous genetic analyses indicated that HTLV-I can be phylogenetically classified into three major lineages: Melanesian, Central African, and Cosmopolitan groups. Recently, more detailed characterization using long terminal repeat sequences (the most variable genomic region) has revealed that the Cosmopolitan group consists of four subtypes: (A) Transcontinental, (B) Japanese, (C) West African, and (D) North African. Most HTLV-I isolates of the same ethnic group from distant locations and those from different groups inhabiting the same area showed phylogenetic similarities. These observations indicate the present distribution of this virus should be interpreted from the anthropological backgrounds of the virus-possessing populations as well as spatial contact among them. Thus, the molecular epidemiology of HTLV-I and its simian counterpart, STLV-I, provides us with important clues for understanding not only the origin and dissemination of this retrovirus but past human movements over the globe.

Africa↗
PubMed2003

Functional analysis of EBV in nasopharyngeal carcinoma cells.

A membrane invasion culture system was used to study the ability of EBV to enhance invasion and migration of nasopharyngeal carcinoma (NPC) cells. Semi-reverse transcriptase-PCR analysis of matrix proteinases and angiogenic factors from EBV-infected, or EBV-positive (EBV+), cells demonstrated different degrees of elevated gene expression. In our animal model, EBV+ tumors grew faster and larger than EBV-free, or EBV-negative (EBV-), tumors and also had clonal EBV terminal repeat sequences. Double-localization of EBV and certain host proteins in EBV+ tumors and biopsy specimens demonstrated that EBV up-regulates host genes only in cells that express those genes but not in cells that do not express them. Double-localization of EBV and host genes in NPC biopsy specimens all showed EBV- tumor cells expressing those host genes. Our data strongly suggest that EBV infection enhances progression of NPC tumor growth. They do not rule out a role for EBV infection in the induction and early promotion of NPC development. Unidentified factors may also enhance NPC tumor growth independent of the effects of EBV.

Animals↗
PubMed1991

Activation of gene expression by human herpesvirus 6 is reporter gene-dependent.

Infection with human herpesvirus 6 (HHV-6) was found to up-regulate expression of human immunodeficiency virus and human T cell leukaemia virus type I (HTLV-I) long terminal repeat sequence (LTR), and herpes simplex virus type 1 (HSV-1) gD chloramphenicol acetyltransferase (CAT) constructs transfected into the T cell line, J. Jhan. Activation by HHV-6 was due to one or more viral proteins produced early in infection and, in the case of the HTLV-I LTR, was synergistic to induction mediated by the HTLV-I tax gene product. Neither the HTLV-I enhancer nor basal promoter elements of the HSV-1 gD gene were essential for activation and no increase in accumulated HTLV-I mRNA was observed due to HHV-6 infection. Induction by HHV-6 was found to be dependent on the reporter construct used, because the CAT gene and, to a lesser extent, the HSV-1 thymidine kinase gene were responsive to HHV-6 infection although no significant activation of growth hormone constructs was observed. Our results bear a strong resemblance to those obtained for the Epstein-Barr virus BMLF1 gene, indicating that the major HHV-6 trans-activator may be a homologue of this gene.

Chloramphenicol O-Acetyltransferase↗
PubMed2004

Identification of putative homology between horse microsatellite flanking sequences and cross-species ESTs, mRNAs and genomic sequences.

In this study the flanking sequences of 1534 horse microsatellites were used in a BLAST search to identify putative human-horse homologies. BLAST searches revealed 129 flanking sequences with significant blastn matches [alignment scores (S) > or = 60 and sum probability values (E) < or = 3.0E-6], also, 25 of these produced significant blastx matches. To provide a reference point in the human genome the flanking sequences with matches were subjected to a BLAT search of the University of California Santa Cruz (UCSC) human genome assembly (July 2003 freeze). Eighty-three of the flanking sequences showed high similarity to sequence of known or putative human genes and the remaining 46 demonstrated high similarity to human intragenic regions. Interestingly, 87 of the microsatellites showed conservation of the tandem repeat in addition to flanking regions. Overall, 41 of the microsatellites had been mapped in the horse and of these 37 localized to the expected syntenic location. The other four did not and represent new putative regions of human-horse synteny. The results of this study contribute 79 new putative human-horse homologies, increasing the density of markers on the human-horse comparative map.

Animals↗
PubMed1995

Antibodies to Pf155/RESA and circumsporozoite protein of Plasmodium falciparum in paired maternal-cord sera from Nigeria.

Paired maternal-cord serum samples were analysed for antibodies to the Pf155/RESA and circumsporozoite protein (CSP) antigens of Plasmodium falciparum. Malaria parasites were found in 2.6% (3/117) of cord blood and 22.4% (26/116) of maternal samples. Immunofluorescence assays detected P. falciparum-specific IgG antibodies in all paired samples while P. falciparum-specific IgM was detected in 5.8% (7/121) of cord samples. The positivity rates for antibodies to Pf155/RESA and (NANP)6 but not (EENV)6, a C-terminal repeat sequence of Pf155/RESA, were significantly higher in maternal as compared with cord samples. Seropositivity rates to Pf155/RESA and (EENV)6 were not related to maternal parity group while positivity rates to the (NANP)6 peptide were higher in primiparae and multiparae of > or = 4 parity. These data confirm the transplacental transfer of P. falciparum-specific antibodies and the higher incidence of malaria parasitaemia in primiparae. The presence of P. falciparum-specific IgM in some cord samples suggests intrauterine sensitization of the foetus to malarial antigens.

Adolescent↗
PubMed1985

Subcellular localization of the product of the long open reading frame of human T-cell leukemia virus type I.

Human T-cell leukemia virus type I (HTLV-I) is a retrovirus associated with adult T-cell leukemia and lymphoma. In addition to containing the gag, pol, and env genes of the chronic leukemia viruses, the genome of HTLV-I contains a long open reading frame (LOR) located between the 3' end of the envelope gene and the 3' long terminal repeat sequence (LTR). It has been suggested that a protein of 42 kilodaltons that is encoded by the LOR region may participate in both trans-acting transcriptional regulation of the viral LTR as well as in the transforming properties of HTLV-I. It is reported here that a significant fraction of the 42-kilodalton HTLV LOR product is located in the nucleus of HTLV-I-infected transformed lymphocytes, a finding that is consistent with its proposed functions.

Cell Fractionation↗
PubMed1992

Involvement of Pf155/RESA and cross-reactive antigens in Plasmodium falciparum merozoite invasion in vitro.

Lines of Plasmodium falciparum FCR3 either expressing or not expressing the blood-stage antigen Pf155/RESA were used to analyze the possible involvement of this antigen in the merozoite invasion process in vitro. Antibodies from human sera, affinity purified on synthetic peptides corresponding to C-terminal repeated sequences in Pf155/RESA, were shown to inhibit merozoite invasion of both types of parasites with similar efficiency. Reversal of the invasion inhibition by fusion proteins containing repeated sequences of Pf155/RESA but not of the cross-reactive antigens Ag332 and Pf11.1 indicated that the inhibitory antibodies had similar target antigens in both Pf155/RESA+ and Pf155/RESA- parasites that involved cross-reacting epitopes present in Pf155/RESA. Rabbit antibodies specific for Pf155/RESA repeats inhibited merozoite invasion of Pf155/RESA expressing parasites efficiently but had no or very small effect on the invasion of Pf155/RESA-deficient parasites. In contrast, rabbit antibodies specific for Ag332 repeats as well as human antibodies affinity purified on synthetic Ag332 peptides inhibited merozoite invasion of both types of parasites with high efficiency. A similar inhibition pattern was seen with the human monoclonal antibody 33G2, which has specificity for Ag332 but also cross-reacts with Pf155/RESA and Pf11.1. Taken together, our data suggest that Pf155/RESA and related cross-reactive antigens as well as Ag332 are involved in the merozoite invasion process and may constitute targets for invasion inhibitory antibodies.

Animals↗
PubMed1982

Transposition of the carbenicillin-hydrolyzing beta-lactamase gene.

We isolated a new transposon Tn2101, from plasmid Rms433 in Enterobacter cloacae. Tn2101 encoded the formation of type IV (carbenicillin-hydrolyzing) beta-lactamase and multiple resistance to streptomycin, sulfanilamide, spectinomycin, and mercury in addition to ampicillin. Tn2101 was transposable between conjugative (or nonconjugative) plasmids and the host chromosome. Transposition occurred independently of the general recombination ability of the host cell. Tn2101 had a molecular size of 9.5 x 10(6) and contained short inverted repeat terminal sequences.

Anti-Bacterial Agents↗
PubMed1996

The tyrT locus of Escherichia coli B.

The tyrT (tRNA(1TYr)) locus of Escherichia coli B differs structurally from that of K-12 strains by the absence of 2 of 3.14 terminal repeat sequences.

Base Sequence↗
PubMed2007

Upstream AP1- and CREB-binding sites confer high basal activity on the adeno-associated virus type 5 capsid gene promoter.

In contrast to the prototype adeno-associated virus type 2 (AAV2), the capsid gene P41 promoter of AAV5, within viral constructs that lack inverted terminal repeat sequences, displays a high basal level of expression in 293 cells in the absence of coinfecting adenovirus. Here we demonstrate that this was due to differences in the relative strengths of the core promoter elements and to the presence of active binding sites for the transcription factors CREB and AP1 within the upstream region of P41 that are absent from the AAV2 capsid gene promoter P40. These differences also governed the relative basal activity of the AAV capsid gene promoters within near-full-length viral genomes.

Base Sequence↗
PubMed1980

Fine-structure mapping and functional analysis of temperature-sensitive mutants in the gene encoding the herpes simplex virus type 1 immediate early protein VP175.

Herpes simplex virus (HSV)-specific proteins fall into at least three kinetic classes whose synthesis is sequentially and coordinaely regulated. Temperature-sensitive (ts) mutants of one complementation group (1-2) are defective in the transition from immediate early to early and late protein synthesis. To elucidate the function of the 1-2 gene product in the HSV type 1 replicative cycle, nine ts mutants in this group were mapped by fine-structure analysis and characterized members of the group lie within the terminally repeated sequences of the S region of the genome. Fine-structure genetic and physical mapping permitted the mutations to be ordered within these sequences. Because it has been shown that the message for VP175 and the DNA template specifying this protein extend beyond the limits of the physical map of the mutations, it follows that the mutations must lie within the structural gene for VP175. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that most members of the group overproduced the immediate early proteins VP175, -136, -110, and -63 and markedly underproduced early and late proteins at the nonpermissive temperature. In temperature shiftup experiments, it was fund that the synthesis of early and late proteins ceased, whereas the synthesis of immediate early proteins began again. Thus, it is postulated that VP175 is (i) involved in the transition from immediate early to early protein synthesis, (ii) requird continuously to maintain early protein synthesis, (iii) autoregulated, acting to inhibit immediate early protein synthesis.

Chromosome Mapping↗
PubMed1980

Avian oncovirus mutant (SE21Q1b) deficient in genomic RNA: characterization of a deletion in the provirus.

We have previously described a nonconditional mutant of avian sarcoma virus (SE21Q1b) which fails to package viral RNA (Gallis et al., Virology 94:146-161, 1979; Linial et al., Cell 15:1371-1381, 1978). Quail cells transformed by SE21Q1b contain normal amounts of intracellular viral mRNA's for src, env, and gag-pol and release particles with the density of normal virus containing a typical complement of virion proteins, including reverse transcriptase. These virions are noninfectious for both chicken and quail cells and contain primarily cellular rather than viral RNA. Analysis by gel electrophoresis of the cellular DNA of quail cells transformed by SE21Q1b after restriction endonuclease digestion indicated the presence of a single provirus. The provirus was located at one site in the genome of the host cell and was flanked by the characteristic terminally repeated sequences derived from the 3' and 5' ends of viral RNA. The only defect detected in the SE21Q1b provirus was a deletion of ca. 150 base pairs of DNA somewhere between 300 and 600 bases from the left (gag-pol) end of the provirus. Analyses of the proviral DNA of cells transformed by wild-type recombinants between SE21Q1b and leukosis viruses reveal that the recombinants no longer contain this deletion. The deletion, therefore, defines a region on the viral RNA which is required for correct packaging of the virion RNA.

Animals↗