Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The results of the present study permit the explanation of one of the mechanisms of the interconnection between the regulatory systems of cAMP and 2-5A. cAMP-dependent regulation of 2'-PDE was found to involve phosphorylation of the specific protein inhibitor. Originally, a similar way of regulation of the enzyme activity was discovered for protein phosphatase I. This enzyme has a specific protein inhibitor type 1, which is phosphorylated by cAMP-dependent protein kinase and is activated by phosphorylation (18). It is interesting that the molecular weights of 2'-PDE protein inhibitor and of the inhibitor type 1 of protein phosphatase I are essentially the same. There is also a certain similarity between the above described mechanism and phosphorylation of the regulatory subunit of cAMP-dependent protein kinase type 2. The regulatory subunit can also act as a protein inhibitor of the enzyme and change its properties as a result of phosphorylation (19). The results obtained permit as well a more detailed explanation for cAMP-dependent inhibition of cell proliferation. Evidently, cAMP elevation causes activation of cAMP-dependent phosphorylation which, in turn, leads to the induction of 2-5A synthetase and inhibition of 2'-PDE. As a result of variations in the activities of these enzymes, the level of 2-5A rises. The latter brings about the changes characteristic of the resting state. They involve activation of RNase L and the succeeding acceleration of RNA hydrolysis, inhibition of protein synthesis and cell proliferation. The resting state is characterized by a rapid turnover of macromolecules due to their intensive degradation (20). The above described scheme suggested that the rapid turnover of RNA during inhibition of cell proliferation can be partially accounted for by activation of 2-5A-dependent RNase L. Thus, it can be thought that at least one of the mechanisms of the antiproliferative effect of cAMP-dependent phosphorylation of proteins involves cAMP-dependent elevation of intracellular 2-5A. Evidently, a number of properties of the resting cells are determined by the elevated content of 2-5A. Finally, it should be noted that the interconnection between the systems of cAMP and 2-5A is a multiple process. We have earlier demonstrated (12) that 2-5A activates cAMP phosphodiesterase in NIH 3T3 cell homogenates. These data suggest that the mutual regulation of cAMP and 2-5A levels involves the negative feedback mechanism (Fig. 8).
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PMID:Regulation of 2-5 A phosphodiesterase activity by cAMP-dependent phosphorylation: mechanism and biological role. 300 Jan 46

3'-Deoxyadenosine (3'dA, cordycepin)-substituted analogs of 2-5A core 5'-monophosphate (p5'A2'p5'A2'p5'A) were examined for their sensitivity toward degradation by the 2'-phosphodiesterase activity in cytoplasmic extracts of mouse L cells. The analogs, p5'(3'dA)-2'p5'A2'p5'A, p5'(3'dA)2'p5'A2'p5'(3'dA) and p5'A2'p5'A2'p5'(3'dA) were degraded at a rate comparable to p5'A2'p5'A2'p5'A itself. On the other hand, under the assay conditions examined p5'A2'p5'(3'dA)2'p5'A, like p5'(3'dA)2'p5'(3'dA)2'p5'(3'dA), was completely resistant to degradation. The data imply that sensitivity to the 2',5'-phosphodiesterase activity of mouse L cells requires the presence of 3'-hydroxyl moiety in the penultimate nucleotide.
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PMID:2',5'-Phosphodiesterase activity depends upon the presence of a 3'-hydroxyl moiety in the penultimate position of the oligonucleotide substrate. 349 4

In order to study interrelationships between the components of the interferon enzyme system and the cyclic AMP system, NIH 3T3 cells were incubated in the presence of theophylline or adrenaline that cause a rise of intracellular cAMP, respectively, through inhibition of phosphodiesterase of cAMP and activation of adenylate cyclase. In doses that caused a transient, 2-to 3-fold elevation of the cAMP level, theophylline and adrenaline elicited about 2.5-fold elevation of 2',5'-oligoadenylate synthetase (2-5A synthetase) activity. This increase could be prevented by actinomycin D. This suggests that the elevation of the enzyme activity in the cells was due to a transcription-dependent induction process. Theophylline and adrenaline treatment of the cell cultures also led to a 2-to 3-fold fall of the activity of the phosphodiesterase of 2',5'-oligoadenylate (2'-phosphodiesterase). This effect of adrenaline was prevented by propanolol but not by actinomycin D. In the case of adrenaline, the fall of 2'-phosphodiesterase activity was accompanied by at least 5-fold increase in the enzyme activity which did not occur if actinomycin D was present in the culture. Similarities and differences between these effects and those induced by interferon are discussed. It is concluded that cAMP is an important regulator of the enzyme system of the 2',5'-oligoadenylate metabolism. 2',5'-Oligoadenylate, in turn, was found to act on the activity of phosphodiesterase of cyclic AMP. The cAMP phosphodiesterase activity in the NIH 3T3 cell lysates was activated 2- to 2.5-fold at physiological concentrations (10(-9) to 10(-7) M) of both the phosphorylated form of oligoisoadenylate, ppp(5'A2'p)n5'A2'OH, and the dephosphorylated form, HO(5'A2'p)25'A2'OH. The phosphorylated form of oligoisoadenylate also activated partially purified preparations of cAMP phosphodiesterase. The data obtained in this study allow us to consider cAMP and 2',5'-oligoadenylate as the key metabolites that may be used in the cells to form a complex, interconnected, multifunctional circuit that involves the interferon enzyme system and the system of cyclic AMP metabolism and governs essential cell functions, as regulation of RNA metabolism and protein synthesis, cell growth and differentiation.
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PMID:A study on the relationship between the interferon enzyme system and the system of cyclic nucleotide metabolism. 608 24

Treatment of NIH 3T3 cells with adenylate cyclase activator adrenaline (10(-6) M) or cAMP phosphodiesterase inhibitor theophylline (10(-3) M) was shown to lead to intracellular cAMP elevation followed by a 2.0-to 2.5-fold increase in the 2',5'-oligoadenylate synthetase activity. This process was blocked by actinomycin D. The rise in the intracellular cAMP level was also followed by a 3-4-fold decrease in the activity of 2'-phosphodiesterase. Propranolol prevented this inhibition but actinomycin D produced only a negligible effect on the process. Incubation of the cell homogenate with purified catalytic subunit of cAMP-dependent protein kinase and ATP also resulted in a decrease of 2'-phosphodiesterase activity. These results indicate that cAMP is involved in the regulation of enzymes of the 2',5'-oligoadenylate system. The possibility that certain biological functions of cAMP are implemented via 2',5'-oligoadenylate-dependent processes is discussed.
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PMID:Cyclic AMP-dependent regulation of activities of synthetase and phosphodiesterase of 2',5'-oligoadenylate in NIH 3T3 cells. 632 57

We describe the properties of a 2',3'-cyclic nucleotide 2'-phosphodiesterase (EC 3.1.4.16), found in Fusarium culmorum, which hydrolyzes nucleoside 2',3'-cyclic monophosphates to nucleoside 3'-phosphates. In contrast with a similar enzyme found in bacteria, the Fusarium enzyme does not exhibit nucleotidase activity and does not show a requirement for metal ions, but is inhibited by micromolar concentrations of Cu++ and Zn++, and is very stable to heat. This cyclic phosphodiesterase hydrolyzes the four major nucleoside 2',3'-cyclic monophosphates and has greater affinity for purine (Kms for Ado-2',3'-P = 0.3 mM and for Guo-2',3'-P = 0.1 mM) than for pyrimidine nucleotides (Kms for Cyd-2',3'-P = 0.6 mM and for Urd-2',3'-P = 2 mM). The respective Vmax for Urd-2',3'-P; Cyd-2',3'-P; Ado-2',3'-P; and Guo-2',3' are 100:45:16:5. The efficacy of the phosphodiesterase to hydrolyze the four major 2',3' cyclic nucleotides (based on the relative values of Vmax/Km) is not significantly different. The Fusarium enzyme differs from a previously described 2',3' cyclic phosphodiesterase from Neurospora, in that it is inactive on 3',5'-nucleoside monophosphates and nucleoside 2' or 3' phosphates.
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PMID:2',3'-cyclic nucleotide 2'-phosphodiesterase from Fusarium culmorum. 1081 2

A-74528 is a recently discovered natural product of Streptomyces sp. SANK 61196 that inhibits 2',5'-oligoadenylate phosphodiesterase (2'-PDE), a key regulatory enzyme of the interferon pathway. Inhibition of 2'-PDE by A-74528 reduces viral replication, and therefore shows promise as a new type of antiviral drug. The complete A-74528 gene cluster, comprising 29 open reading frames, was cloned and sequenced, and shown to possess a type II polyketide synthase (PKS) at its core. Its identity was confirmed by analysis of a mutant generated by targeted disruption of a PKS gene, and by functional expression in a heterologous Streptomyces host. Remarkably, it showed exceptional end-to-end sequence identity to the gene cluster responsible for biosynthesis of fredericamycin A, a structurally unrelated antitumor antibiotic with a distinct mode of action. Whereas the fredericamycin producing strain, Streptomyces griseus, produced undetectable quantities of A-74528, the A-74528 gene cluster was capable of producing both antibiotics. The biosynthetic roles of three genes, including one that represents the only qualitative difference between the two gene clusters, were investigated by targeted gene disruption. The implications for the evolution of antibiotics with different biological activities from the same gene cluster are discussed.
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PMID:Cloning, sequencing, heterologous expression, and mechanistic analysis of A-74528 biosynthesis. 2055 Jan 25

A-74528 is a C30 polyketide natural product that functions as an inhibitor of 2',5'-oligoadenylate phosphodiesterase (2'-PDE), a key regulatory enzyme of the interferon pathway. Modulation of 2'-PDE represents a unique therapeutic approach for regulating viral infections. The gene cluster responsible for biosynthesis of A-74528 yields minute amounts of this natural product together with considerably larger quantities of a structurally dissimilar C30 cytotoxic agent, fredericamycin. Through construction and analysis of a series of knockout mutants, we identified the genes necessary for A-74528 biosynthesis. Remarkably, the formation of six stereocenters and the regiospecific formation of six rings in A-74528 appear to be catalyzed by only two tailoring enzymes, a cyclase and an oxygenase, in addition to the core polyketide synthase. The inferred pathway was genetically refactored in a heterologous host, Streptomyces coelicolor CH999, to produce 3 mg/L A-74528 in the absence of fredericamycin.
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PMID:Analysis and refactoring of the A-74528 biosynthetic pathway. 2344 97

The scintillation proximity assay (SPA) technology has been widely used to establish high throughput screens (HTS) for a range of targets in the pharmaceutical industry. PDE12 (aka. 2'- phosphodiesterase) has been published to participate in the degradation of oligoadenylates that are involved in the establishment of an antiviral state via the activation of ribonuclease L (RNAse-L). Degradation of oligoadenylates by PDE12 terminates these antiviral activities, leading to decreased resistance of cells for a variety of viral pathogens. Therefore inhibitors of PDE12 are discussed as antiviral therapy. Here we describe the use of the yttrium silicate SPA bead technology to assess inhibitory activity of compounds against PDE12 in a homogeneous, robust HTS feasible assay using tritiated adenosine-P-adenylate ([3H]ApA) as substrate. We found that the used [3H]ApA educt, was not able to bind to SPA beads, whereas the product [3H]AMP, as known before, was able to bind to SPA beads. This enables the measurement of PDE12 activity on [3H]ApA as a substrate using a wallac microbeta counter. This method describes a robust and high throughput capable format in terms of specificity, commonly used compound solvents, ease of detection and assay matrices. The method could facilitate the search for PDE12 inhibitors as antiviral compounds.
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PMID:Development of a Scintillation Proximity Assay (SPA) Based, High Throughput Screening Feasible Method for the Identification of PDE12 Activity Modulators. 2733 27