Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal murine spleen cells were sensitized to syngeneic myeloid leukemia cells by RNA extracted from the lymph nodes and spleens of Hartley guinea pigs immunized with the murine leukemia cells. Sensitization mediated by RNA was an active process that required physiologic temperature and at least a 10-minute incubation. RNA extracted from unimmunized guinea pigs of guinea pigs immunized with normal spleen cells failed to sensitize the mouse spleen cells. Sensitization was specifically directed toward leukemia cells, whereas the spleen cells remained unreactive toward normal spleen or bone marrow cells. The sensitizing moiety was RNA itself inasmuch as it was inactivated by RNase and not by DNase or pronase. Preparations whose RNA patterns on sucrose density centrifugation gave evidence of degradation of the RNA did not sensitize normal spleen cells. These studies demonstrate that xenogeneic immune RNA can specifically sensitize normal spleen cells to syngeneic myeloid leukemia cells.
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PMID:Sensitization in vitro to murine myeloblastic leukemia cells by xenogeneic immune RNA. 28 68

The binding of AS RNase and CM-AS RNase to leukaemic cells from patients with chronic lymphatic leukaemia was detected by indirect immunofluorescence. Leucocytes from normal donors or from patients with other hemoblastoses did not bind RNase. Experiments with lymphocytes from leukaemic patients and the lymphoblastoid cell lines in tissue culture revealed that both AS RNase solutions are probably bound mainly to leukaemic B lymphocytes.
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PMID:The binding of bull seminal ribonuclease and its carboxymethylated derivative to human leukaemic cells. 28 6

A new species of RNA has been isolated from several different cell lines, both oncornavirus producing and non-producing. This RNA, which we designate 5.9-S RNA is present in the cellular cytoplasmic fraction at very low concentration (approximately 1% of the quantity of 4-S RNA), but it accumulates to much higher levels in two murine oncornaviruses, Moloney murine sarcoma leukemia virus complex and Gross leukemia virus, where it represents as much as 10% of the low-molecular-weight RNA fraction associated with the 70-S RNA genome. The electrophoretic mobility and fingerprint analysis of T1 RNase digest products show that this species of RNA is approximately 160-165-residues long, and can be unequivocally distinguished from all previously described species of RNA in this size range.
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PMID:5.9-S RNA, a new RNA characterized in several mammalian cell lines. 40 71

Moloney leukemia virus activated both the classical and alternative pathways of human complement. About 500,000 virions were required to detect activation of the classical pathway whereas 5,000 times as many virions were necessary to initiate the alternative pathway, indicating that in this system only the former is of biological significance. Disruption of the virus with Triton X-100 destroyed its ability to initiate the alternative pathway without affecting its ability to activate the classical pathway. After ultracentrifugation of disrupted virus the active component could be recovered in the supernate and was isolated by isoelectric focusing in granulated gels. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic and analysis and cyanogen bromide digestion studies revealed that the activity resided in a methionine-containing protein having a pI of 7.5 and a molecular weight of approximately equal to 15,000 daltons. The purified protein interacts strongly with Clq and efficiently activates Cl. RNase and lipolytic enzymes had no effect on the isolated protein but incubation with trypsin resulted in loss of activity. Enzymatic digestion studies of surface-labeled virus indicate that the active protein is a viral membrane protein. On the basis of these results it is concluded that the complement receptor of Moloney leukemia virus is the surface protein p15E.
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PMID:Lysis of oncornaviruses by human serum. Isolation of the viral complement (C1) receptor and identification as p15E. 63 50

The cross-linked dimer of bovine pancreatic RNase (M.W. 28,000) is significantly more effective than the monomer in inhibiting tumor development in mice when administered i.p. 1 day after inoculation with sarcoma 180J ascites cells. Animals bearing solid tumors were not affected. In AKR/J mice with advanced leukemia, a single i.p. injection of 100 mug of the dimer led to about 50% reduction in the enlarged lymph nodes and the spleen at 24 hr. The half-life of the dimer in the bloodstream has been determined to be 10 min in rats and 6 min in mice, compared to values of 5 and 3.5 min, respectively, for the monomer. Analyses of the tissues of untreated leukemic mice for RNase and RNase inhibitors show that the tumor tissues are not deficient in RNase activity. Considerations of possible mechanisms of action of the dimer indicate that other basic proteins in this size range may merit examination as cytostatic agents toward transformed cells.
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PMID:Comparison of antitumor activities of pancreatic ribonuclease and its cross-linked dimer. 97 50

Mice were actively immunized against Friend leukemia virus tumorigenesis by vaccination with cell-free homogenates derived from infected splenocytes emulsified in Freund's adjuvant. Adoptive immunity was also achieved by transferring splenocytes from actively immunized donor animals intravenously into syngeneic recipient animals challenged with the virus. Furthermore, RNA-rich extracts derived from spleens of actively immunized donor animals were capable of transferring immunity to FLV leukemia when injected into recipient animals challenged with the virus. The "immune RNA," when incubated with normal splenocytes in vitro, followed by washing, resulted in a cell population that also induced adoptive immunity after transfer to normal animals challenged with virus either before, simultaneously with, or after injection of the treated splenocytes. RNase, but not DNase or other enzymes, inactivated the biologie activity of the protective RNA from immune donors. In addition, isogeneic mouse serum that contained neutralizing antibody to FLV also inhibited the protective effect of the specific RNA; sera from control mice immunized with unrelated antigens failed to neutralize the specific RNA. These results indicate that an RNA extract that contains a virus-associated or -induced antigen is formed in the spleens of actively immunized animals and possesses the ability to either directly induce protective immunity in recipient animals challenged with virus or, indirectly, to convert normal splenocytes in vitro to adoptively confer immunity to similar recipients. Further investigations concerning the mechanism by which such immunogenic RNA functions in vivo and in vitro, as well as the physicochemical nature of the RNA complex, especially that portion associated with the tumor virus-associated antigen, are needed.
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PMID:Discussion paper: protective immunity in leukemic mice treated with specific "immunogenic" RNA. 106 68

Ribonuclease activity in cell-free thymus homogenates was elevated for five strains of mice genetically predisposed toward leukemia or reticulum cell neoplasms (AKR, C58, PL, RF, and SJL). Such increased activity was directed against polyuridylic acid and was observed in 8-wk old mice, well before the onset of neoplastic transformation. Similarly, white blood cell ribonuclease activity was elevated in mice of the strains AKR, C2H/He, PL and RF. Statistical analysis indicated that such elevated activity in these strains related to their high incidence of spontaneous neoplastic disease. Elevated ribonuclease activity thus represents a new biochemical marker relating to the genetic propensity of some strains of mice to die prematurely of spontaneous neoplasia.
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PMID:Elevated ribonuclease activity in the thymus and white blood cells of genetically cancer prone mice. 109 92

Rapidly labelled high molecular weight nuclear RNA from lymphocytes of chronic lymphocytic leukaemia was analysed for ribonuclease-stable adenylate-rich and double-stranded regions. The polyadenylate content corresponds to 0.4-0.5 percent and the content of double-stranded sequences to 2-4 percent of the total nucleotides. Partial association of polyadenylate segments with double-stranded regions was found by comparative analysis of (3H)-adenosine and (3H)-uridine labelled ribonuclease-stable RNA before and after thermal denaturation. Comparison with normal lymphocytes shows lower proportions of polyadenylate-containing RNA binding to poly(U)-Sepharose in leukaemia cells than in normals. Partial degradation of rapidly labelled high molecular weight RNA was found in leukaemia cases with low white cell counts.
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PMID:Heterogeneous nuclear rna from lymphocytes of chronic lymphocytic leukaemia: adenylate-rich and double-stranded regions. 112 45

Topoisomerases catalyse the interconversion of topological isomers of DNA and have key roles in nucleic acid metabolism. Human cells express two distinct type II topoisomerase isozymes, designated topoisomerase II alpha (170 kDa form) and topoisomerase II beta (180 kDa form). We have isolated cDNA clones encoding the beta isozyme from a human B-cell library. The proposed coding region for the topoisomerase II beta protein is 4,863 nucleotides long and would encode a polypeptide with a calculated M(r) of 182,705. The predicted topoisomerase II beta protein sequence shows striking similarity (72% identical residues) to that of the human alpha isozyme, and homology to topoisomerase II proteins from Drosophila, yeast and bacteria. Regions of greatest amino acid sequence divergence lie at the extreme N-terminus and over a C-terminal domain comprising approximately 25% of the total protein. We have quantified the level of topoisomerase II beta mRNA in a panel of human tumour cell lines of different origin using an RNase protection assay, and compared the level to that of topoisomerase II alpha mRNA. Topoisomerase II beta mRNA was expressed in haemopoietic, epithelial and fibroblast cell lines, although to different extents, with U937 cells (promonocytic leukaemia) showing a particularly high level. There was no obvious relationship in terms of level of expression between the topoisomerase II alpha and beta genes. We have localised the gene encoding topoisomerase II beta protein to chromosome 3p24 in the human genome.
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PMID:Isolation of cDNA clones encoding the beta isozyme of human DNA topoisomerase II and localisation of the gene to chromosome 3p24. 133 83

Upon reverse transcription and cloning manipulations with virion RNAs of several plant viruses, namely beet yellows virus, brome mosaic virus, and potato virus X, we came across a significant background synthesis of cDNA on the virion RNA template in vitro independent of exogenous primers added. When tested with beet yellow virus RNA template, several commercial preparations of avian myeloblastosis virus (AMV) reverse transcriptase showed the background activity monitored by the [alpha-32P]dNTP incorporation in vitro, while the enzyme from murine moloney leukemia virus (MMLV) was found strictly exogenous-primer-dependent. To detect possible nucleic acid contaminations in reverse transcriptase, the enzyme preparations from several commercial sources were incubated with [gamma-32P]ATP and polynucleotide kinase. The labeled material from AMV reverse transcriptase preparations comigrated with a tRNA marker in polyacrylamide gels and was found to be RNase-sensitive. The MMLV reverse transcriptase preparations were free from such a contamination. These results indicate that the exogenous-primer-independent cDNA synthesis by some AMV reverse transcriptases could be due to a contaminating tRNA (or its low-molecular-weight degradation products) serving as an endogenous primer.
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PMID:Exogenous primer-independent cDNA synthesis with commercial reverse transcriptase preparations on plant virus RNA templates. 138 74


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