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Krause D, Panet A, Arad G, Dieffenbach CW, Silverman RH. Independent regulation of ppp(A2'p)nA-dependent RNase in NIH 3T3, clone 1 cells by growth arrest and interferon treatment. J Biol Chem 1985; 260:9501-7. [PMID: 4019482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The regulation of ppp(A2'p)nA-(2-5A)-dependent RNase (RNase L or RNase F) was investigated in NIH 3T3, clone 1 cells using 2-5A-binding and nuclease activity assays. Minimal levels of 2-5A-dependent RNase were detected in actively dividing clone 1 cells; these levels were independently induced by growth arrest or interferon treatment. Accordingly, levels of the RNase were enhanced during growth arrest by confluency regardless of the presence or absence of interferon or antibody to interferon in the media. Measurement of 2-5A-dependent RNase was unaffected by the addition of any of six different proteinase inhibitors to the cells prior to extraction. The expression of 2-5A-dependent RNase in growth-arrested, interferon-treated cells was still relatively low (about one-third to one-half of that found in similarly treated murine Ehrlich ascites tumor cells). Although this amount of 2-5A-dependent RNase could not be detected by 2-5A-mediated ribosomal RNA cleavage, the activity was identified using a more sensitive novel assay for 2-5A-dependent RNase. In addition, introduction of 2-5A or poly(I) X poly(C) into growth-arrested, interferon-treated cells resulted in some inhibition of protein synthesis. The results indicated that the expression of 2-5A-dependent RNase in NIH 3T3, clone 1 cells is regulated under different physiological conditions and that low levels of 2-5A-dependent RNase were insufficient to significantly inhibit encephalomyocarditis virus replication.
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Krause D, Panet A, Arad G, Dieffenbach CW, Silverman RH. Independent regulation of ppp(A2'p)nA-dependent RNase in NIH 3T3, clone 1 cells by growth arrest and interferon treatment. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39392-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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203
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Coleman DJ, Lizzi FL, Silverman RH, Helson L, Torpey JH, Rondeau MJ. A model for acoustic characterization of intraocular tumors. Invest Ophthalmol Vis Sci 1985; 26:545-50. [PMID: 3884539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Human intraocular tumors and tumors derived from human tumor cell lines grown subcutaneously in the athymic nude mouse were scanned by diagnostic ultrasound. Radiofrequency scan data were converted to digital form and analyzed in the frequency domain. Characteristics of normalized power spectra were found to be significantly different among human spindle cell malignant melanomas, mixed/epithelioid malignant melanomas, metastatic carcinomas, and hemangiomas. Significant differences, as well, were found between implanted primary skin malignant melanomas and adenocarcinomas of the lung, colon, and stomach. Comparison of spectral properties of human intraocular and implanted tumors revealed that human spindle cell malignant melanomas and implanted melanomas exhibit similar characteristics. Human intraocular metastatic tumors from the lung were found to exhibit characteristics similar to those of implanted lung tumors. These results indicate that the implantation of human tumor cell lines in the nude mouse may provide a very useful model for application of diagnostic and therapeutic ultrasound modalities to human intraocular tumors.
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204
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Coleman DJ, Lizzi FL, Driller J, Rosado AL, Burgess SE, Torpey JH, Smith ME, Silverman RH, Yablonski ME, Chang S. Therapeutic ultrasound in the treatment of glaucoma. II. Clinical applications. Ophthalmology 1985; 92:347-53. [PMID: 3991122 DOI: 10.1016/s0161-6420(85)34028-9] [Citation(s) in RCA: 114] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Focused, high-intensity therapeutic ultrasound was used to treat 69 selected patients with uncontrollably elevated intraocular pressure (IOP). This new technique selectively thins scleral collagen, and produces focal damage to the ciliary epithelium. These tissue modifications provide a reduction in IOP pressure to 25 mmHg or less in 83% of patients with a minimum three-month follow-up period.
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Silverman RH. Functional analysis of 2-5A-dependent RNase and 2-5a using 2',5'-oligoadenylate-cellulose. Anal Biochem 1985; 144:450-60. [PMID: 3993910 DOI: 10.1016/0003-2697(85)90141-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
2-5A is an intracellular effector that has been implicated in interferon action, hormonal regulation, and cell growth control. 2-5A action is mediated through its activation of 2-5A-dependent RNase (RNase L, RNase F). Affinity resins [2-5A-cellulose and core (2-5A)-cellulose] were chemically synthesized for purification and immobilization of 2-5A-dependent RNase from mouse L cells and rabbit reticulocyte lysates. The breakdown of poly(U)-[3'-32P]Cp to acid-soluble fragments was demonstrated using the 2-5A-dependent RNase:2-5A -cellulose complex; this activity was enhanced by adding (free) 2-5A. In contrast, RNase activity was measured from the 2-5A-dependent RNase:core (2-5A)-cellulose complex only after the addition of free 2-5A. The rabbit reticulocyte 2-5A-dependent RNase is activated only by tetramer or higher oligomers of 2-5A; therefore there was breakdown of poly(U)-[3'-32P]Cp using core (2-5A)-cellulose-bound reticulocyte 2-5A-dependent RNase after addition of tetramer 2-5A but there was no poly(U) degradation in the presence of trimer 2-5A. The absence of significant general nuclease in the assays was demonstrated by the resistance to breakdown of poly(C)-[3'-32P]Cp (not susceptible to 2-5A-dependent RNase). Moreover, core (2-5A)-cellulose was used to develop a sensitive (subnanomolar) assay for the detection of authentic 2-5A. 2-5A, or the material to be tested, was added to mouse L-cell 2-5A-dependent RNase:core (2-5A)-cellulose complex in the presence of poly(U)-[3'-32P]Cp. The concentration of 2-5A in the sample could be measured from the amount of poly(U) degradation. Several closely related analogs of 2-5A were tested and found to be completely inactive. The technology described herein may be applied to the study of the regulation of 2-5A-dependent RNase, the detection of 2-5A from cells and tissues, and other aspects of the 2-5A system.
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206
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Krause D, Silverman RH, Jacobsen H, Leisy SA, Dieffenbach CW, Friedman RM. Regulation of ppp(A2'p)nA-dependent RNase levels during interferon treatment and cell differentiation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 146:611-8. [PMID: 2578957 DOI: 10.1111/j.1432-1033.1985.tb08695.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The intracellular effector oligonucleotides ppp(A2'p)nA (n = 2- greater than or equal to 4) regulate the breakdown of RNA by activating ppp(A2'p)nA-dependent RNase. Cellular levels of this RNase were demonstrated to be regulated during differentiation of murine embryonal carcinoma cells. An induction of this RNase by interferon was demonstrated in each of three differentiated cell types (F9 clone 9, PYS, and PSA 5E) by analyzing rRNA breakdown following the introduction of ppp(A2'p)nA into the intact cells. In contrast, in three undifferentiated embryonal carcinoma cell lines (F9, PC13 clone 5, and Nulli 2A) there was little if any ppp(A2'p)nA-dependent RNase either with or without interferon pretreatment. These results were confirmed by affinity labeling of the RNase in cell-free systems. Addition of the proteinase inhibitor, leupeptin, to the cell lysis buffer was necessary to stabilize the RNase against cleavage to discrete breakdown products. Moreover, during differentiation of PC13 clone 5 cells by retinoic acid and N6,O2'-dibutyryl-adenosine 3',5'-monophosphate there was a gradual induction of ppp(A2'p)nA-dependent RNase. The expression of this RNase is, therefore, greatly enhanced during cell differentiation. In addition, the double-stranded-RNA-dependent protein kinase was investigated and was found to be interferon-inducible in all of the cell lines regardless of the state of cell differentiation.
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Coleman DJ, Lizzi FL, Silverman RH, Ellsworth RM, Haik BG, Abramson DH, Smith ME, Rondeau MJ. Regression of uveal malignant melanomas following cobalt-60 plaque. Correlates between acoustic spectrum analysis and tumor regression. Retina 1985; 5:73-8. [PMID: 3901166 DOI: 10.1097/00006982-198500520-00002] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Parameters derived from computer analysis of digital radio-frequency (rf) ultrasound scan data of untreated uveal malignant melanomas were examined for correlations with tumor regression following cobalt-60 plaque. Parameters included tumor height, normalized power spectrum and acoustic tissue type (ATT). Acoustic tissue type was based upon discriminant analysis of tumor power spectra, with spectra of tumors of known pathology serving as a model. Results showed ATT to be correlated with tumor regression during the first 18 months following treatment. Tumors with ATT associated with spindle cell malignant melanoma showed over twice the percentage reduction in height as those with ATT associated with mixed/epithelioid melanomas. Pre-treatment height was only weakly correlated with regression. Additionally, significant spectral changes were observed following treatment. Ultrasonic spectrum analysis thus provides a noninvasive tool for classification, prediction and monitoring of tumor response to cobalt-60 plaque.
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208
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Grimley PM, Rutherford MN, Kang YH, Williams T, Woody JN, Silverman RH. Formation of tubuloreticular inclusions in human lymphoma cells compared to the induction of 2'-5'-oligoadenylate synthetase by leucocyte interferon in dose-effect and kinetic studies. Cancer Res 1984; 44:3480-8. [PMID: 6744275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Exposure of human lymphoblastoid cell cultures to leukocyte interferon initiated the formation of membranous tubuloreticular inclusions (TRI) within the endoplasmic reticulum or perinuclear envelope. In four different cell lines originating from patients with lymphocytic cancers (Daudi, Raji, H-SB2, and SB), this unique ultrastructural effect displayed a log-linear relationship to increasing doses of interferon-alpha and was dose and time dependent. TRI morphogenesis began within 12 hr in Daudi or Raji cells exposed continuously to 500 IU of leukocyte interferon/ml, but only at 20 hr after 2- to 4-hr pulse exposures to 50 to 100 IU/ml. The TRI accumulation, determined by thin-section counts, reached maximal levels of up to 16% of cell sections within 48 to 72 hr. Experiments with Raji cells indicated a decrease in TRI formation during successive cell divisions; detection of TRI after a pulse of interferon was enhanced when DNA replication was arrested. TRI morphogenesis appeared to be independent of several other known biological actions of interferons. It manifested later than the induction of 2'-5'-oligoadenylate synthetase activity which has been correlated with establishment of the antiviral state and occurred in cell lines, including DaudiKIFNR, which resist the growth-inhibitory effects of leukocyte interferon. Participation of new polypeptide synthesis was indicated by experiments with inhibitors of transcription (actinomycin D) or translation (cycloheximide): TRI morphogenesis was blocked when actinomycin D was added 4 hr after interferon and was reduced when cycloheximide was added for the interval of 13 to 23 hr after interferon.
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209
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Jacobsen H, Krause D, Friedman RM, Silverman RH. Induction of ppp(A2'p)nA-dependent RNase in murine JLS-V9R cells during growth inhibition. Proc Natl Acad Sci U S A 1983; 80:4954-8. [PMID: 6576368 PMCID: PMC384166 DOI: 10.1073/pnas.80.16.4954] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We recently reported that interferon induces the synthesis of ppp(A2'p)nA(n = 2 to greater than or equal to 4) (2-5A)-dependent RNase in the murine cell line JLS-V9R. These cells normally contain very low levels of the nuclease; after interferon treatment, however, they develop levels approaching those found in murine L or Ehrlich ascites tumor cells. Here, we report a similar increase in the nuclease levels in JLS-V9R cells during the transition from the subconfluent actively growing state to the confluent stationary phase. Levels of 2-5A synthetase increased in parallel with the nuclease. The induced levels of both the nuclease and synthetase returned to low basal amounts after trypsinization, dilution, and culturing of the cells at subconfluent densities. The addition of anti-murine interferon (alpha + beta) antibodies to the medium did not affect the induction of the nuclease nor could any interferon be detected in the culture supernatants as determined by the lack of antiviral activity. The increase in the enzymes was not, therefore, due to the spontaneous production of interferon. The induction of the nuclease during confluency preceded an inhibition of [3H]-thymidine incorporation by the cells into DNA. The regulation of the 2-5A-dependent RNase in JLS-V9R cells may, therefore, be related to the control of cell growth.
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210
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Silverman RH, Skehel JJ, James TC, Wreschner DH, Kerr IM. rRNA cleavage as an index of ppp(A2'p)nA activity in interferon-treated encephalomyocarditis virus-infected cells. J Virol 1983; 46:1051-5. [PMID: 6190010 PMCID: PMC256583 DOI: 10.1128/jvi.46.3.1051-1055.1983] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
In cell-free systems, 2-5A [ppp(A2'p)nA, n = 2 to greater than or equal to 4] activates a latent endoribonuclease, the 2-5A-dependent RNase, which cleaves rRNA in intact ribosomes into discrete and characteristic products (D. H. Wreschner et al., Nucleic Acids Res. 9:1571-1581, 1981). Here we present Northern blots which have identified the 18S or 28S origins of the cleaved products from rRNA. In addition, identical 3' termini were observed for fragments of 18S rRNA from a HeLa cell-free system incubated with 2-5A and from interferon-treated, encephalomyocarditis virus-infected HeLa cells. The previous assumption of identity of such fragments was based only on comigration on electrophoresis in agarose gels. We conclude that appropriate patterns of cleavage found in RNA isolated from intact cells are an indicator of prior 2-5A-dependent RNase activity. The assay of rRNA cleavage is relatively convenient and unambiguous. Accordingly, in the search for situations in which the 2-5A system may be active, it provides a useful alternative to the direct assay of 2-5A.
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211
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Maheshwari RK, Sreevalsan T, Silverman RH, Hay J, Friedman RM. Tunicamycin enhances the antiviral and anticellular activity of interferon. Science 1983; 219:1339-41. [PMID: 6187067 DOI: 10.1126/science.6187067] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The inhibitory effects of interferon on virus multiplication and cell growth are significantly enhanced by treatment with tunicamycin. Potentiation of antiviral activity was found only with enveloped viruses and not with nonbudding viruses. Changes in the plasma membrane of treated cells may account for this effect, since enveloped viruses bud from the cell surface as a terminal step.
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212
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Jacobsen H, Czarniecki CW, Krause D, Friedman RM, Silverman RH. Interferon-induced synthesis of 2-5A-dependent RNase in mouse JLS-V9R cells. Virology 1983; 125:496-501. [PMID: 6188272 DOI: 10.1016/0042-6822(83)90222-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Interferon treatment of mouse JLS-V9R cells resulted in a 10- to 20-fold increase in the levels of the 2-5A (ppp(A2'p)nA)-dependent RNase. The nuclease was monitored in cell extracts by covalent and noncovalent binding of 32P-labeled 2-5A derivatives to the nuclease and by the appearance of 2-5A-mediated ribosomal RNA cleavage products. Untreated JLS-V9R cells contained very low levels of the nuclease (5-10% of that found in control Ehrlich ascites tumor cells). An increase in the nuclease was first detected between 3 and 6 hr after interferon treatment and was completely inhibited by actinomycin D. Control experiments indicated that the increase in the nuclease was not due to an intracellular redistribution of the enzyme. The results indicate that in JLS-V9R cells, interferon controls the activity of the 2-5A system at two levels: by inducing the synthesis of both the 2-5A-dependent RNase and the 2-5A-synthetase.
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213
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Kerr IM, Cayley PJ, Silverman RH, Knight M. The antiviral action of interferon. Philos Trans R Soc Lond B Biol Sci 1982; 299:59-67. [PMID: 6183696 DOI: 10.1098/rstb.1982.0106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
On interferon treatment cells develop an antiviral state. This requires time and RNA and protein synthesis. At least six polypeptides and two enzymes have been reported to be synthesized in increased amounts in response to interferon and a multiplicity of effects have been attributed to it. Interferon has been reported to inhibit virus growth at the level of the uncoating of the virus, virus RNA and protein synthesis and virus maturation. This has led to the acceptance of a multisite model for interferon action. The evidence for this and for the role of two known interferon-mediated enzymes, the 2-5A synthetase and protein kinase, are reviewed.
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Silverman RH, Watling D, Balkwill FR, Trowsdale J, Kerr IM. The ppp(A2'p)nA and protein kinase systems in wild-type and interferon-resistant Daudi cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 126:333-41. [PMID: 6181993 DOI: 10.1111/j.1432-1033.1982.tb06783.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Daudi cells, a human lymphoblastoid line, are exceptionally sensitive to the growth inhibitory effects of interferon, 1 unit/ml being sufficient to inhibit cell growth. In addition, interferon treatment of these cells severely inhibits the incorporation of exogenous thymidine into DNA and causes cells to accumulate in the G1(G0) at the expense of the S phase of the cell cycle. The possible involvement of ppp(A2'p)nA(n = 2 to less than or equal to 4) in these effects has been investigated. No (less than 1 nM) ppp(A2'p)nA or (A2'p)nA or alternative products of the ppp(A2'p)nA synthetase [e.g. NAD (2'pA)2] were detected in interferon-treated cells. In addition no evidence was obtained for the occurrence of ppp(A2'p)nA-mediated ribosomal RNA cleavage in these cells even after several days of treatment with relatively high doses of interferon. A line of Daudi cells which is resistant to all three of the above effects of interferon was selected. The wild type and resistant lines were compared with respect to the ppp(A2'p)nA and interferon and double-stranded RNA (dsRNA)-mediated protein kinase systems. The resistant line was not receptor-negative as it responded to interferon by the production of elevated levels of the ppp(A2'p)nA synthetase similar to those observed in extracts from wild-type cells. There was no detectable difference between the lines in the levels of the (2'-5')phosphodiesterase responsible for the degradation of ppp(A2'p)nA. There was, however, about a twofold increase in the ppp(A2'p)nA-dependent endoribonuclease activity in response to interferon with extracts from the wild-type but not the resistant cells. In addition, although the dsRNA-dependent protein kinase activity increased in both types of cell there was a striking reduction in the level of protein phosphorylation in general in response to interferon with material from the wild-type but not the resistant cells.
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Wreschner DH, Silverman RH, James TC, Gilbert CS, Kerr IM. Affinity labelling and characterization of the ppp(A2'p)nA-dependent endoribonuclease from different mammalian sources. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 124:261-8. [PMID: 6284502 DOI: 10.1111/j.1432-1033.1982.tb06586.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The ppp(A2'p)nA-dependent endoribonucleases from a number of different mammalian sources have been investigated. The enzyme from reticulocyte lysates shows optimal activity of 50-150 mM KCl and requires the presence of Mg2+. Whilst the enzyme is inactivated after passage of reticulocyte lysates through Sephadex columns in the absence of ATP, it retains full activity provided ATP is included in the column buffer. The activity of the partially purified nuclease was unaffected by the addition of reticulocyte RNase inhibitor, which, in contrast, effectively inhibited other endogenous endonucleases. The ppp(A2'p)nA-dependent Rnase co-purified with a ppp(A2'p)nA-binding protein and with a protein which could be specifically covalently labelled with an oxidised radioactive analogue of ppp(A2'p)nA. This covalent labelling could be carried out either with the partially purified RNase or in crude extracts from rabbit reticulocytes, mouse Krebs and Ehrlich ascites tumour cells and human lymphoblastoid (Daudi) or HeLa cells. In each case the affinity labelled protein migrated to a position corresponding to a apparent molecular weight of about 85 000 on electrophoresis on dodecylsulphate/polyacrylamide gels. In all cases labelling could be prevented by the addition of an excess of unlabelled ppp(A2'p)nA but not, for example, by a similar excess of the biologically inactive dimer ppp(A2'p)'A. It is concluded that the RNase and ppp(A2'p)nA binding activities are likely to reside in the same molecule.
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Silverman RH, Cayley PJ, Knight M, Gilbert CS, Kerr IM. Control of the ppp(a2'p)nA system in HeLa cells. Effects of interferon and virus infection. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 124:131-8. [PMID: 6177533 DOI: 10.1111/j.1432-1033.1982.tb05915.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
HeLa cells have an unusually high level of ppp(A2'p)nA synthetase (n = 2 to greater than or equal to 4) even in the absence of interferon treatment. In accord with this ppp(A2'p)nA and ppp(A2'p)nA-mediated ribosomal RNA cleavage occur naturally in response to encephalomyocarditis virus infection in control as well as in interferon-treated cells. Despite this, in the absence of interferon treatment, encephalomyocarditis virus grows well in these cells. A possible explanation for this paradox is that the ppp(A2'p)nA dependent RNase is lost or inactivated at later times post-infection in control but not in interferon-treated cells. It appears, therefore, to be the prevention by interferon of the virus-mediated inhibition of the ppp(A2'p)n-dependent nuclease rather than the absolute level or induction of the ppp(A2'p)nA synthetase which is crucial for the activity of the ppp(A2'p)nA system in HeLa cells. These results provide evidence for a further level of control in the ppp(A2'p)nA system and show that limited ppp(A2'p)nA-mediated ribosomal RNA cleavage alone is not sufficient to cause an inhibition of virus growth.
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217
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Wreschner DH, James TC, Silverman RH, Kerr IM. Ribosomal RNA cleavage, nuclease activation and 2-5A(ppp(A2'p)nA) in interferon-treated cells. Nucleic Acids Res 1981; 9:1571-81. [PMID: 6164990 PMCID: PMC326782 DOI: 10.1093/nar/9.7.1571] [Citation(s) in RCA: 220] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Ribosomal RNA (rRNA) in intact ribosomes is cleaved into discrete products on incubation of reticulocyte lysates or L-cell extracts with ppp(A2'p)3A. Cleavage of rRNA may, therefore, provide a useful assay for 2-5A (ppp)A2'p)nA; n = 2 to 4) or for the presence of a 2-5A-dependent nuclease. The results with reticulocyte lysates differed from those obtained in the L-cell-free system in that (a) a different RNA cleavage pattern was produced (with added L-cell ribosomes) and (b) cleavage was fully activated by the analogue ppp(A2'p)3A3'pCp. As might be expected from the relatively high levels of 2-5A present in interferon-treated, encephalomyocarditis virus (EMC)-infected L-cells, rRNA extracted from these cells was also cleaved. The cleavage pattern observed overlapped with that obtained on incubation of an L-cell-free system with 2-5A. Thus, not only is 2-5A present, but the 2-5A-dependent nuclease also appears to be active, in interferon-treated, EMC-infected L-cells.
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218
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Silverman RH, Wreschner DH, Gilbert CS, Kerr IM. Synthesis, characterization and properties of ppp(A2'p)nApCp and related high-specific-activity 32P-labelled derivatives of ppp(A2'p)nA. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 115:79-85. [PMID: 7227373 DOI: 10.1111/j.1432-1033.1981.tb06200.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
T4 RNA ligase (EC 6.5.1.3) has been used to link cytidine 3',5'-[5'-32P]bisphosphate or unlabelled cytidine 3',5'-bisphosphate (pCp) covalently to the 3'-OH of individual components of 5'-triphospho-oligo[(2'-5')adenylyl]adenosine [ppp(A2'p)nA with n = 2 or 3] and adenylyl(2'-5')adenylyl(2'-5')adenosine [(A2'p)2A] to yield 5'-triphospho-oligo[(2'-5')adenylyl]adenylyl(3'-5')cytidine 3'-phosphate [ppp(A2'p)nApCp with n = 2 or 3] and adenylyl(2'-5')adenylyl(2'-5')adenylyl(3'-5')cytidine 3'-phosphate (A2'p)2ApCp], respectively. The radioactive products isolated by high-performance liquid chromatography had specific activities greater than 10(6) Ci/mol. These products were found to be effective probes for use in radiobinding and radioimmune assays for ppp(A2'p)nA and (A2'p)nA [M. Knight et al. (1980) Nature 288, 189-192]. ppp(A2'p)nA is unstable in cell-free systems and in intact cells. ppp(A2'p)nApCp, however, was found to be much more stable than ppp(A2'p)nA in extracts of rabbit reticulocytes or Ehrlich ascites tumour cells. (A2'p)2Ap, (A2'p)2ApC (reticulocyte only) or (A2'p)2ApCp were also more stable than unmodified (A2'p)2A in these systems. The results are consistent with a specific degradation pathway for ppp(A2'p)nA which proceeds from the 3' terminus. ppp(A2'p)3ApCp activated the ppp(A2'p)nA-dependent RNase and inhibited protein synthesis in a reticulocyte cell-free system at least as well as unmodified tetramer ppp(A2'p)3A, suggesting that an unmodified 3' terminus is not required for full activity in this system. In extracts from mouse Ehrlich ascites tumour or L-cells, however, ppp(A2'p)nApCp was greater than or equal to 30 fold less active (if directly active at all).
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Williams BR, Brown RE, Gilbert CS, Golgher RR, Wreschner DH, Roberts WK, Silverman RH, Kerr IM. Assay of (2'-5')-oligo(A) synthesized in vitro and the analysis of naturally occurring (2'-5')-oligo(A) from intact cells. Methods Enzymol 1981; 79:199-208. [PMID: 6173665 DOI: 10.1016/s0076-6879(81)79030-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Knight M, Cayley PJ, Silverman RH, Wreschner DH, Gilbert CS, Brown RE, Kerr IM. Radioimmune, radiobinding and HPLC analysis of 2-5A and related oligonucleotides from intact cells. Nature 1980; 288:189-92. [PMID: 6159552 DOI: 10.1038/288189a0] [Citation(s) in RCA: 208] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The enzyme (2-5A synthetase) which synthesizes ppp(A2'p)nA where n=2 to 4 (collectively referred to as 2-5A) is widely distributed in a variety of cells and tissues in amounts which increase response to interferon and vary with growth and hormone status. 2-5A activates a nuclease which inhibits protein synthesis. The non-phosphorylated 'core' of 2-5A ((A2'p)nA, n=2 to 4) can inhibit DNA synthesis and cell growth. Here we describe convenient and sensitive radioimmune (RI) and radiobinding (RB) assays for core and 2-5A. In combination with more satisfactory high performance liquid chromatography (HPCL) methods using reverse-phase C18 columns, these assays have been used to detect core and 2-5A in crude extracts from interferon-treated cells. The novel 2-5A synthetase products NAD2'p5' A2'p5'A and A5'p45'A2'p5'A2'p5'A (ref. 13), which can also be detected using the RB assay, were not found in significant amounts. The natural occurrence of core has not been described previously.
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Silverman RH, Atherly AG. The search for guanosine tetraphosphate (ppGpp) and other unusual nucleotides in eucaryotes. Microbiol Rev 1979; 43:27-41. [PMID: 379576 PMCID: PMC281460 DOI: 10.1128/mr.43.1.27-41.1979] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Silverman RH. Employing the movable dental chair (MDC) for expanded auxiliary function. QUINTESSENCE INTERNATIONAL, DENTAL DIGEST 1978; 9:83-9. [PMID: 296430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Silverman RH, Atherly AG. Unusual effects of 5a,6-anhydrotetracycline and other tetracyclines. Inhibition of guanosine 5'-diphosphate 3'-diphosphate metabolism, RNA accumulation and other growth-related processes in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 518:267-76. [PMID: 350279 DOI: 10.1016/0005-2787(78)90183-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
5a,6-Anhydrotetracycline was discovered to be unique among several tetracycline derivatives tested in its ability to inhibit RNA accumulation in vivo at low concentration (20 microgram/ml and less). In addition, in vivo protein, DNA, and guanosine 5'-diphosphate 3'-diphosphate (ppGpp) synthesis were completely inhibited by 20 microgram/ml 5a,6-anhydrotetracycline. ppGpp decay in a spoT strain was inhibited by 20 microgram/ml 5a,6-anhydrotef RNA synthesis by a 5a,6-anhydrotetracycline may be due, in part, to reduced UTP and CTP synthesis. The effects of tetracyclines on in vitro ppGpp synthesis by crude stringent factor in the absence of ribosomes were investigated. It was determined that of six tetracyclines tested, four strongly inhibited the reaction (oxytetracycline, chlorotetracycline, dedimethylaminotetracycline, and tetracycline) whereas 5a,6-anhydrotetracycline gave a moderate inhibition and alpha-6-deoxyoxytetracycline resulted in only a slight reduction in ppGpp synthesis. It is proposed that tetracyclines interfere with factors involved in ppGpp metabolism and function.
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Silverman RH, Atherly AG. Mouse embryos fail to synthesize detectable quantities of guanosine 5'-diphosphate 3'-diphosphate. Dev Biol 1977; 56:200-5. [PMID: 320067 DOI: 10.1016/0012-1606(77)90163-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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