Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

In order to explore the possibility of supplanting the requirement of a 5'-triphosphate moiety for the activation of the 2-5A-dependent endonuclease (RNase L) of mouse L-cells, two new tetrameric analogues of 2-5A were synthesized. The first tetramer, obtained by both a modified prebiotic synthetic approach as well as a phosphite triester solid phase oligonucleotide synthesis method, was p5'A2'p5'A2'p5'(br8A)2'p5'(br8A). The second oligonucleotide was derived from the former by a sequence involving periodate oxidation, reaction with n-hexylamine, and cyanoborohydride reduction, resulting in conversion of the 2'-terminal adenosine residue to 9-(3'-aza-4'-hexyl-1',2',3',4'-tetradeoxyhexopyranos-1(1)-yl)-8-++ +bromoadenine. Both of these oligomers, bearing only 5'-monophosphate groups, were found to be as potent as 2-5A itself as activators of the RNase L of mouse L-cells.
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PMID:A new and potent 2-5A analogue which does not require a 5'-polyphosphate to activate mouse L-cell RNase L. 141 9

The oligonucleotide ppp5'A2'p5'A2'p5'A, known as 2-5A, is a potent translational inhibitor involved in some aspects of interferon action. To explore the specific function of the charged 5'-triphosphate moiety, we prepared a series of congeners in which the 5' region was hypermodified. Thus, uronic acid derivatives were substituted for the 5' terminal adenosine residue of 2-5A. Compounds 9, 10, 11 and 12 carried adenosine 5'-uronic acid, ethyl adenosine 5'-uronate, adenosine 5'-uronamide, and adenosine 5'-(N-ethyl)uronamide, respectively, in place of the 5' terminal adenosine triphosphate moiety of 2-5A. While all the analogues showed some weak interaction with the 2-5A-dependent endonuclease (RNase L), compound 9 showed the strongest binding ability, and while unable to activate the mouse RNase L, could activate human RNase at a concentration 100-fold greater than that required for the parent 2-5A. This result suggests that the function of the 5'(poly)phosphate moiety of 2-5A may be fulfilled by some other anionic moiety.
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PMID:Synthesis and biological activity of uronic acid analogues of 2-5A[5'-O-triphosphoryladenylyl(2----5')adenylyl-(2'----5')adenosine]. 152 4

RNase L activated by 2-5A (a series of 2'-5'-linked adenylic oligoribonucleotides) is a key enzyme of the interferon system. To study RNase L (endonuclease L) in intact cells independently of intracellular 2-5A and of its activity, we have developed polyclonal antibodies against RNase L. RNase L from mouse spleen was purified on a column of 2-5A-Sepharose and used to immunize rabbits in co-injection with polyadenylic-polyuridylic acid as adjuvant. Antibodies were purified by chromatography on Affi-Gel blue and 2-5A-Sepharose-immobilized RNase L. These polyclonal antibodies immunoprecipitate the 80- and 40-kDa forms of RNase L in mouse spleen. In Western blot, only the 80-kDa form of RNase L is recognized by these antibodies. These purified antibodies were used to localize RNase L in the cytoplasm of intact mouse NIH 3T3 cells by immunofluorescence. The cytoplasmic localization of RNase L was confirmed by its 2-5A binding activity after cellular fractionation.
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PMID:Polyclonal antibodies against RNase L. Subcellular localization of this enzyme in mouse cells. 170 39

Analogues of the 2',5'-linked adenylate trimers monophosphate (p5'A2'p5'A2'p5'A) containing 8-hydroxypropyladenosine, 8-bromoadenosine, and 8-hydroxyadenosine in the first, second, and third nucleotide positions were tested for their ability to bind to and activate RNase L of mouse L cells. p5'AHPr2'p5'AHPr2'p5'AHPr (pAHPr3) (1b) and p5'ABr2'p5'ABr2'p5'ABr (pABr3) (1d) were markedly decreased in ability to bind to the 2-5A dependent endonuclease. On the other hand, analogue of the 2',5'-linked adenylate trimer monophosphate substituted by 8-hydroxyadenosine in the first, second, and third nucleotide position was bound about as well as parent 2-5A [pppA(2'p5'A)2] (p3A3) (1e) to RNase L. Additionally, p5'AOH2'p5'AOH2'p5'AOH (pAOH3) (1c) was as active as parent 2-5A in the rRNA cleavage assay, while pAHPr3 (1b) and pABr3 (1d) were devoid of activity. The 8-substituted analogues of 2-5A were more resistant to the degradation by the (2',5') phosphodiesterase. Finally of particular interest was monophosphate, pAOH3 (1c) which possessed nearly 100% of the translation inhibitory activity of 2-5A triphosphate itself. These results suggest that changes in the base-sugar torsion angles of 2-5A may modulate both binding to and activation of mouse L cell RNase L.
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PMID:Purine 8-substitution modulates the ribonuclease L binding and activation abilities of 2',5'-oligoadenylates. 202 89

Addition of extract of interferon (IFN)-treated HeLa cells to transcription reactions containing activated reovirion cores decreases the yield of viral mRNA (C. Baglioni, A. De Benedetti, and G. J. Williams, 1984, J. Virol. 52, 865-871). The 2'5'-oligo(A) (2-5A)-dependent endonuclease (RNase L) cleaves specifically viral mRNA, but little 5'-triphosphate 2-5A is recovered from these reactions by DEAE-cellulose chromatography. However, in the present study we detected microM concentrations of 2-5A derivatives by binding to RNase L. Similar results were obtained when the synthetic double-stranded RNA poly(I) X poly(C) was incubated with extract from IFN-treated cells: microM concentrations of 2-5A were detected by the binding assay, but little rRNA was degraded by RNase L. 2-5A derivatives which inhibited the activation of RNase L by authentic 2-5A were eluted from DEAE-cellulose with 90 mM KCl. These inhibitors were also formed by incubating purified 2-5A with HeLa cell extract. These results indicated that 2-5A was synthesized in the incubations with reovirion cores or poly(I) X poly(C), but that it was in large part degraded to compounds inhibitory for RNase L. IFN-treated HeLa cells were incubated with poly(I X C), but little rRNA degradation was detected in spite of the presence of high concentrations of 2-5A in these cells. Most of this 2-5A was eluted with 90 mM KCl from DEAE-cellulose and was inhibitory for RNase L. This indicated that 2-5A was degraded to inhibitory derivatives also in intact cells. The structure of the degradation products of 2-5A has not been established, but they contain free terminal phosphate(s), since their binding to RNase L and the inhibition of this enzyme is abolished by digestion with phosphatase.
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PMID:Inhibition of 2',5'-oligo(A)-dependent endoribonuclease by 2',5'-oligo(A) degradation products. 242 11

We have synthesized a series of 2-5A (ppp5'-A2'p5'A2'p5'A) analogs in which each adenosine residue has been sequentially replaced by inosine: viz., ppp5'I2'p5'A2'p5'A, ppp5'A2'p5'I2'p5'A, and ppp5'A2'p5'A2'p5'I. These transformations enabled us to delineate the role of each of the three purine N-6 amino groups of 2-5A in determining oligonucleotide binding to and activation of the 2-5A-dependent endoribonuclease, RNase L. With the RNase L activity of both mouse L cells and human Daudi lymphoblastoid cells, we found that the N-6 amino group of the first adenosine nucleotide residue (from the 5'-terminus) is of crucial importance in determining binding to the endonuclease; however, removal of the N-6 amino moieties of the second or third adenosine nucleotide residues resulted in only a minimal decrease in binding to the endonuclease. On the other hand, conversion of the third adenosine residue to inosine effected a dramatic (10,000-fold compared to 2-5A) loss in ability to activate the nuclease; however, execution of the same N-6 amino group conversion at either the first or second adenosine residue did not cause a major change in nuclease activation ability when the accompanying decreased endonuclease binding was considered. These results clearly demonstrate that the N-6 amino group of the first adenosine residue of 2-5A is critical in RNase L binding whereas the N-6 amino function of the third adenosine residue of 2-5A is crucial for the activation of RNase L.
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PMID:Respective role of each of the purine N-6 amino groups of 5'-O-triphosphoryladenylyl(2'----5')adenylyl(2----5')adenosine in binding to and activation of RNase L. 298 55

Through a combination of chemical and enzymatic approaches a series of sequence-specific tubercidin-substituted ppp5'A2'p(5'A2'p)n5'A (n = 1 to about 10; 2-5A) analogues were generated. In addition to the previously developed methodology of Imai and Torrence [Imai, J., & Torrence, P.F. (1985) J. Org. Chem. 50, 1418-1420], a new approach to synthesis of 2',5'-linked oligonucleotides utilized adenosine in 3',5' linkage as a precursor to the targeted 5'-terminus of the desired product. For instance, A3'p5'A could be condensed under conditions of lead ion catalysis with tubercidin 5'-phosphate to give A3'p5'A2'p5'(c7A). Treatment with the 3',5'-specific nuclease P1 led to p5'A2'p5'(c7A). The combined use of the above procedures led to the synthesis of p5'(c7A)2'p5'A2'p5'A, p5'A2'p5'(c7A)2'p5'A, p5'A2'p5'A2'p5'(c7A), and p5'A2p5'(c7A)2'p5'(c7A), which were converted to their corresponding 5'-triphosphates by the usual methods. Evaluation of these analogues for their ability to bind to and activate the 2-5A-dependent endonuclease (RNase L) of mouse L cells showed that there were small changes (less than or equal to 10-fold) in the ability of the four tubercidin analogues to bind to RNase L. However, whenever the first and/or third adenosine nucleotide units were replaced by tubercidin, a dramatic decrease in ability to activate RNase L occurred. Only the second (from the 5'-terminus) adenosine residue could be replaced by tubercidin without any effect on RNase L activation ability.
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PMID:Respective role of each of the purine N7 nitrogens of 5'-O-triphosphoadenylyl(2'----5')adenylyl(2'----5')adenosine in binding to and activation of the RNase L of mouse cells. 303 Apr 8

The levels of a (2'-5')An-dependent endonuclease (RNase L) were determined in extracts prepared from murine L cells and Ehrlich ascites tumor (EAT) cells by measuring specific binding of protein to a labeled derivative of (2'-5')An, (2'-5')A3[32P]pCp. RNase L levels were found to depend both on interferon (IFN) treatment and on cell growth conditions. Treatment of murine L cells and EAT cells with 100-2,000 IRU IFN beta or IFN gamma resulted in a similar 2-4-fold increase in the levels of RNase L when cells were present at low density. The levels of RNase L were also shown to increase 2-3-fold as cells approached saturation density. Serum-starved cells also displayed relatively high levels of RNase L. RNase L levels in cells maintained at high cell density did not change appreciably following treatment with IFN beta or IFN gamma. Regulation of RNase L levels by cell growth conditions as well as by IFN beta or IFN gamma treatment suggests that RNase L may play an important role in regulating the levels of cellular mRNAs as well as acting to degrade viral RNAs.
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PMID:(2'-5')An-dependent endoribonuclease: enzyme levels are regulated by IFN beta, IFN gamma, and cell culture conditions. 314 77

To investigate the relative importance of each of the ribose 3'-hydroxyl groups of 2-5A (ppp5' A2'p5'A2'-p5' A) in determining binding to and activation of the 2-5A-dependent endonuclease (RNase L), the 3'-hydroxyl functionality of each adenosine moiety of 2-5A trimer triphosphate was sequentially replaced by hydrogen. The analog in which the 5'-terminal adenosine was replaced by 3'-deoxyadenosine (viz. ppp5'(3'dA)-2'p5' A2'p5' A) was bound to RNase L as well as 2-5A itself and was only 3 times less potent than 2-5A as an activator of RNase L. On the other hand, when the second adenosine unit was replaced by 3'-deoxyadenosine (viz. ppp5' A2'p5'(3'dA)2'p5' A), binding to RNase L was decreased by a factor of eight relative to 2-5A trimer and, even more dramatically, there was a 500-1000-fold drop in ability to activate the 2-5A-dependent endonuclease. Finally, when the 3'-hydroxyl substituent was converted to hydrogen in the 2'-terminal residue of 2-5A, a significant increase in both binding and activation ability occurred. We conclude that only the 3'-hydroxyl group of the second (from the terminus) nucleotide residue of 2-5A is needed for effective activation of RNase L.
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PMID:Only one 3'-hydroxyl group of ppp5' A2'p5'A2'p5' A (2-5A) is required for activation of the 2-5A-dependent endonuclease. 333 33

We have examined the effect of sodium butyrate, a potent inducer of differentiation in various cell systems, on the steady state RNA level and transcriptional activity of the c-myc gene in Burkitt's lymphoma cells. Following sodium butyrate treatment a rapid decrease of c-myc RNA was observed in all Burkitt's lymphoma cell lines studied, irrespective of the type of translocation, the location of the breakpoint relative to c-myc or of the association with EBV. Since cellular genes induced by interferon are suspected to play a role in c-myc regulation we have studied transcription of the 2-5A synthetase gene in sodium butyrate-treated Burkitt's lymphoma cells. Transcriptional activity and steady state mRNA levels of the 2-5A synthetase gene were induced by sodium butyrate. The time course of induction excluded, however, that the decrease of c-myc RNA is caused by induction of the 2-5A synthetase/RNase L endonuclease system. The reduction of c-myc RNA is caused, at least in part, by a reduced transcription rate, as shown by nuclear run-on analysis. The fact that sodium butyrate is capable of downregulating a truncated c-myc gene indicates that an important target site of transcriptional regulation is located outside the region encompassing the upstream regulatory sequences, the dual promoters and the leader region.
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PMID:Truncation does not abrogate transcriptional downregulation of the c-myc gene by sodium butyrate in Burkitt's lymphoma cells. 369 77


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