Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of various tumor initiators and promoters on induction of persisting Epstein-Barr virus (EBV) in different lines of lymphoblastoid cells was analyzed. Neither five polycyclic aromatic hydrocarbons, amongst them potent tumor initiators (e.g., 7,12-dimethylbenz[a]anthracene), nor the potent (ultimate) liver carcinogen N-acetoxy-N-2-acetylamino-fluorene induced EBV. A series of compounds, representing three classes of tumor-promoting diterpene esters (e.g., 12-O-tetradecanoylphorbol-13-acetate), efficiently induced EBV in persistently infected cells. The concentration required for maximal induction ranged between 0.5 and 100 nM. Some nonpromoting diterpenes (phorbol, 4alpha-phorbol-12,13-didecanoate, and ingenol) did not induce EBV. However, the nonpromoters, resiniferatoxin and 12-deoxyphorbol-13-decatrienoate, were effective, whereas anthralin, a tumor promoter, did not induce EBV. In three lines of EBV genome-carrying cells (Raji, NC-37, and RPMI 64-10) only abortive induction was noted, leading exclusively to synthesis of early antigen. In cells of lines with low spontaneous virus release (P3HR-1, B95-8, and QIMR-Wil), upon treatment with tetradecanoylphorbol acetate, approximately 20-40 times more viral DNA was recovered as compared to untreated controls. Viral DNA from tetradeca-noylphorbol acetate-induced cultures revealed the same restriction endonuclease cleavage pattern as viral DNA obtained from noninduced cells. Within 10 days after induction, release of infectious virus increased approximately by one order of magnitude. Prostaglandins, reported to be released after treatment with tumor promoters, were ineffective in virus induction under the conditions tested.
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PMID:Tumor initiators and promoters in the induction of Epstein-Barr virus. 21 19

RNA was extracted from the Burkitt lymphoma-derived cell line Raji and from Burkitt lymphoma tumor biopsies, isotope labeled in vitro by iodination with 125I, and hybridized to electrophoretically separated restriction endonuclease fragments of Epstein-Barr virus DNA on nitrocellulose membranes. The results indicated that only certain parts of the Epstein-Barr virus genome are represented as polyribosomal RNA in Raji cells, with a pronounced dominance of RNA sequences complementary to a 2.0 x 10(6)-dalton segment of Epstein-Barr virus DNA located close to the left end of the viral genome. A map of virus-specific polyribosomal RNA sequences was constructed, which indicated that a minimum of three regions of the Epstein-Barr virus genome are expressed in Raji cells. Total-cell RNA preparations from five Burkitt lymphoma biopsies contained RNA sequences homologous to the same regions of Epstein-Barr virus DNA as polyribosomal RNA from Raji cells, albeit at different relative proportions.
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PMID:Identification of transcribed regions of Epstein-Barr virus DNA in Burkitt lymphoma-derived cells. 23 90

The open reading frames of the phosphoprotein pp58 (BMRFI) and the deoxyribonuclease (BGLF5) of the Epstein-Barr-virus (EBV) strain M-ABA were cloned in the baculovirus expression vectors pAc373 and pAc360 and expressed in the Spodoptera frugiperda (SF158) insect cells. The recombinant phosphoprotein pp58 expressed in SF158 cells was recognized by the anti-pp58 rabbit anti-sera which were generated by immunizing rabbits with a TrpE-BMRFI fusion protein expressed in E. coli. DNA-cellulose chromatography showed that the recombinant pp58 exhibited DNA-binding activities. Immunofluorescence, immunoblot and ELISA analysis indicated that sera from patients with nasopharyngeal carcinoma (NPC) contained antibodies against pp58. The recombinant EBV DNase expressed in SF158 cells was recognized by the anti-EBV DNase rabbit anti-sera which were generated by immunizing rabbits with a TrpE-C-terminal part of BGLF5 fusion protein expressed in E. coli. The anti-EBV DNase rabbit anti-sera recognized also a protein of about 52 kDa in the EBV-harboring human B-cell lines Raji, Jijoye, B95-8, M-ABA and BL74 induced by TPA and n-butyrate. The recombinant EBV DNase exhibited exonuclease and endonuclease activities, a requirement for magnesium, and a high pH optimum (8.0). Its enzyme activities could be inhibited by sera from NPC patients and anti-EBV DNase rabbit anti-sera. Comparable studies of Raji EBV-DNase and recombinant EBV-DNase implied that recombinant EBV-DNase could also be used in the enzyme activity assay for the detection of NPC. In contrast to the enzyme inhibition test, immunofluorescence and immunoblot analysis demonstrated that the recombinant EBV DNase exhibited only a weak immunological reaction with NPC sera.
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PMID:Immunological characterization of the Epstein-Barr virus phosphoprotein PP58 and deoxyribonuclease expressed in the baculovirus expression system. 165 Mar 30

The Escherichia coli hemolysin (HlyA) and Pasteurella haemolytica leukotoxin (LktA) are cytolytic toxins encoded by genes belonging to the recently described RTX gene family. These cytotoxins are, respectively, 1,023 and 953 amino acids in length and are encoded by genes within identically organized operons. They share 45% amino acid sequence identities but differ in their target cell specificities. In vitro-derived recombinant hybrid genes between hlyA and lktA were constructed by using restriction endonuclease sites created by oligonucleotide site-directed mutagenesis. The cytolytic activity of hybrid proteins was investigated using as targets sheep erythrocytes and two cultured cell lines from different species (BL3, bovine leukemia-derived B lymphocytes; and Raji, human B-cell lymphoma cells). HlyA is cytolytic to all three cell types. LktA lyses only BL3 cells. Among the hybrid proteins displaying cytolytic activity, the striking finding is that the hemolytic activity of several LktA-HlyA hybrids was independent of any cytolytic activity against either cultured cell species. The hemolytic activity was associated with the HlyA region between amino acids 564 and 739. Structures that are critical for HlyA cytolytic activity against BL3 or Raji cells were destroyed when LktA-HlyA and HlyA-LktA hybrids were made, respectively, at amino acid positions 564 and 739 of HlyA. In contrast to HlyA, which lysed the two different cultured cell lines with equal efficiency, Lkt-HlyA hybrids possessing the amino-terminal 169 residues of LktA lysed BL3 cells more efficiently than Raji cells. This suggests that a significant but not exclusive element of the LktA ruminant cell specificity resides in the amino-terminal one-fifth of the protein. A molecular model of the functional domains of HlyA and LktA is presented.
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PMID:Identification of RTX toxin target cell specificity domains by use of hybrid genes. 193 78

Three human cell lines of lymphoid (Molt-3 and Raji) or myeloid (HL-60) origin were maintained in vitro under zinc-sufficient or zinc-deficient conditions. Under these conditions, cell proliferation, viability and mode of death (apoptotic or necrotic) were assessed. All three cell types decreased their proliferative capacity and viability under conditions of zinc deficiency. Cell death in the HL-60 and Raji cultures occurred primarily via apoptosis, while most cells in zinc-deficient Molt-3 cultures died via necrosis. Apoptosis in zinc-deficient cultures of HL-60 and Raji cells was characterized by a slow decline in culture viability as cells with condensed and fragmented nuclear DNA appeared. These morphological changes were accompanied by an increase in cell buoyant density, which allowed separation of viable apoptotic cells from their non-apoptotic counterparts by means of percoll stepdensity gradients. Necrosis in zinc-deficient Molt-3 cultures was characterized by rapid loss of cell culture viability as these cells underwent direct lysis. Intact necrotic cells were easily identified by the flocculated state of their chromatin as well as the decreased basophilia of their cytoplasm. Analysis of DNA from apoptotic HL-60 and Raji cells revealed that internucleosomal DNA degradation, indicative of endogenous endonuclease activation, had occurred, whereas the nuclear DNA of necrotic Molt-3 cells remained relatively unfragmented. The different modes of cell death evoked may reflect the relative sensitivities of cells of these lineages to zinc levels in vivo.
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PMID:Programmed cell death (apoptosis) in lymphoid and myeloid cell lines during zinc deficiency. 199 65

Infection of a human lymphoblastoid B cell line (Raji cells) with type D retroviruses, originally isolated either from subhuman primates (MPMV, LV) or from permanent human cell lines (PMFV, HeLaV, HEp-2V) led to the production of type D retrovirus particles. Subsequent cocultivation of uninfected and virus-producing Raji cells was employed for the generation of sufficient amounts of covalently closed circular DNA molecules (cccDNA). Highest amounts of cccDNA were obtained after cocultivation of virus-producing Raji cells and homologous uninfected cells at a ratio of 1 to 3 for 72 hr. The cccDNAs of type D retroviruses migrated at about 4.3 kbp compared to lambda DNA/HindIII markers. Digestion of cccDNAs with restriction endonucleases which have one recognition site generated molecules of approximately 8 kbp. The restriction endonuclease site analysis of the cccDNA of type D retroviruses revealed a genomic heterogeneity among the different isolates.
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PMID:Isolation and characterization of covalently closed circular proviral DNA molecules of several type D retroviruses isolated from human cell lines. 302 12

Human Raji target cells DNA is degraded by the introduction of single-strand breaks (alkali-sensitive sites) upon lymphocyte-mediated lysis. This type of DNA degradation appears earlier and is more extensive in lymphocyte-than in antibody + complement-mediated lysis of Raji cells, regardless of the species of effector lymphocytes (human or mouse). Mouse P815 target cell DNA is extensively fragmented (yielding 200 base pair fragments) when human or mouse lymphocytes are used to lyse P815. Thus, these observations indicate that both human and mouse target cell DNA are affected during lymphocyte-mediated lysis. Moreover, the pattern of DNA degradation in target cells lysed by effector lymphocytes is characteristic of the target cell species, suggesting that DNA degradation proceeds through the activation of target cell endonuclease(s).
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PMID:DNA of human Raji target cells is damaged upon lymphocyte-mediated lysis. 307 99

Epstein-Barr virus (EBV) nuclear antigen (EBNA) was purified from the Burkitt lymphoma line Raji and its EBV DNA-binding properties were characterized. EBNA binding protected fragments of about 30 bp of B95-8 cell-derived EBV DNA from an excess of DNase I. Human anti-EBNA antibodies prevented DNA binding. Purified extracts from EBNA-negative cells did not protect EBV DNA against DNase I digestion. Mapping of the EBV DNA fragments protected from endonuclease (EcoRI, HindIII, SalI) digestion revealed many binding sites. Similar results were obtained following mixing of crude cell extracts and HindIII-digested fragments of EBV DNA and subsequent immunoprecipitation of the EBNA-DNA complex. In experiments involving the analysis of EBV DNA, fragments were protected from DNase I digestion by purified EBNA.
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PMID:Interaction between Epstein-Barr virus-determined nuclear antigen (EBNA) and the viral DNA. 609 16

An enzymatic activity that synthesizes (2'-5')-oligo(A) from ATP is induced in animal cells treated with interferon. This activity, designated (2'-5')A polymerase, is also elevated in human lymphoblastoid Daudi and Raji cells treated with hydrocortisone. The polymerase activity increases significantly after 24 hr of treatment and declines when hydrocortisone is removed from the culture medium. The product of the enzyme prepared from hydrocortisone-treated cells is indistinguishable from (2'-5')oligo(A) synthesized with polymerase of interferon-treated cells either by an endonuclease activation assay or by chromatographic analysis. The increase in (2'-5')A polymerase is not mediated by secretion of interferon by hydrocortisone-treated cells; less than 1 unit of interferon per ml is present in the culture medium during treatment with this glucocorticoid hormone. Moreover, this increase is related to the concentration of hydrocortisone in the culture medium and is inhibited by the addition of cortexolone. This steroid interferes with the interaction between glucocorticoid hormones and their receptor. Cortexolone has no effect, however, on the induction of (2'-5')A polymerase by interferon. The synthetic glucocorticoid dexamethasone also increases the polymerase activity. Experiments with inhibitors show that such an increase requires RNA and protein synthesis.
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PMID:Increased levels of (2'-5')oligo(A) polymerase activity in human lymphoblastoid cells treated with glucocorticoids. 616 67

A comparative analysis of three Epstein-Barr virus DNAs from American patients with infectious mononucleosis (B95-8, Cherry, and Lamont) and four Epstein-Barr virus DNAs from African patients with Burkitt lymphoma (AG876, W91, Raji, and P3HR-1) indicated that the usual format of Epstein-Barr virus DNA includes a variable number of direct repeats of a 0.35 X 10(6)-dalton sequence (TR) at both ends of the DNA, a 9 X 10(6)-dalton sequence of largely unique DNA (Us), a variable number of repeats of a 2 X 10(6)-dalton sequence (IR), and a 89 X 10(6)-dalton sequence of largely unique DNA (UL). Within UL there was homology between DNA at 26 X 10(6) to 28 X 10(6) daltons and DNA at 93 X 10(6) to 95 X 10(6) daltons. The relative sequence order (TR, US, IR, UL, TR) did not vary among "standard" Epstein-Barr virus DNA molecules of each isolate. B95-8 DNA had an unusual deletion extending from 91 X 10(6) to 100 X 10(6) daltons, and P3HR-1 DNA had an unusual deletion extending from 23.5 X 10(6) to 26 X 10(6) daltons. There was sufficient variability among the EcoRI and BamHI fragments of the DNAs to identify each isolate specifically. However, we discerned no distinguishing features for the two geographic or pathogenic origins of the seven isolates. Three intracellular DNAs (Raji, Lamont, and Cherry) and one virion DNA (P3HR-1) were heterogenous in molecular organization and had subpopulations of rearranged or defective molecules. Some regions, particularly 59 X 10(6) to 63 X 10(6) daltons and sequences around TR, frequently participated in rearrangements. Restriction endonuclease maps of the standard and rearranged DNAs of the seven isolates are presented.
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PMID:Epstein-Barr virus DNA. IX. Variation among viral DNAs from producer and nonproducer infected cells. 626 34


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