Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.37 (CNPase)
 539 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myelin basic protein, an 80-kilodalton (kDa) protein in rat oligodendrocytes, and an 80-kDa basic protein in neuroblastoma x neonatal Chinese hamster brain explant hybrids were phosphorylated extensively when the cells were treated with either phorbol esters (TPA) or diacylglycerols (e.g., oleyoyl-acetylglycerol). TPA-stimulated phosphorylation was inhibited by pre-incubation with 50 microM psychosine (galactosyl-sphingosine), confirming that it is mediated through the phospholipid-dependent protein kinase C (PK-C). Surprisingly, phosphorylation of these proteins was inhibited by incubation of cells with agents which result in activation of cyclic-AMP-dependent protein kinase (dibutyryl cyclic AMP or forskolin). In contrast, phosphorylation of other nonbasic proteins, for example, the oligodendrocyte-specific 2',3'-cyclic nucleotide phosphohydrolase, was stimulated under these conditions (Vartanian et al.: Proceedings of the National Academy of Sciences of the United States of America 85:939, 1988). The possible role of cyclic AMP in activating specific phosphatases or restricting the availability of diacylglycerol for PK-C activation is discussed.
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PMID:Differential regulation of basic protein phosphorylation by calcium phospholipid and cyclic-AMP-dependent protein kinases. 277 6

Clonal cell line D6P2T, subcloned from an ethylnitrosourea-induced tumor line D6 of the rat peripheral nervous system, has been characterized with particular attention to galactolipid metabolism. Galactosylcerebroside and sulfatide synthesis and expression on the cell surface are highly regulated in D6P2T cells by mechanisms involving serum- and cyclic AMP-mediated pathways. These cells also express 2',3'-cyclic nucleotide 3'-phosphohydrolase (Wolfgram protein W1a) and laminin. In contrast, myelin basic protein and antigen HNK-1 were not detected. Line D6P2T appears to be a semi-differentiated Schwann cell model, which offers interesting possibilities for studies of galactolipid synthesis, transport, and sorting.
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PMID:Regulated galactolipid synthesis and cell surface expression in Schwann cell line D6P2T. 282 98

In an effort to determine the factors that stimulate myelin synthesis, we investigated the mechanism by which dibutyryl cyclic AMP induces the activity of the myelin enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP; EC 3.1.4.37), in C6 glioma cells. Immunotitration experiments and measurements of the accumulation of [35S]methionine-labeled CNP showed that dibutyryl cyclic AMP increased the amount of CNP in the cells but not the catalytic activity per molecule of the enzyme. Moreover, inhibition of protein synthesis with cycloheximide abolished induction of enzyme activity. Dibutyryl cyclic AMP doubled the rate of CNP synthesis but had no effect on the half-life of the enzyme (approximately 33 h). The induction was partially blocked by the inhibitors of mRNA synthesis, cordycepin or alpha-amanitin. Thus, cyclic AMP induces the synthesis of CNP.
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PMID:Induction of myelin components: cyclic AMP increases the synthesis rate of 2',3'-cyclic nucleotide 3'-phosphohydrolase in C6 glioma cells. 298 29

The oligodendroglial enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), is a valuable marker for expression of oligodendroglial differentiation in glial primary cultures, and the inducibility of this enzyme by dibutyryl-3',5'-cyclic AMP (dBcAMP) appears to be limited to immature or developing oligodendroglia. To investigate the relationship between the induction of CNP and the sterol biosynthetic pathway, primary cultures of glia dissociated from the brains of newborn rats were maintained in 10% fetal calf serum (FCS) and exposed to 1 mM dBcAMP on day 7 in culture. Cultures so treated for either 48 h or 72 h demonstrated a three- to fourfold induction of CNP specific activity. The magnitude of this induction was not affected when the cholesterol content of the culture medium was reduced by greater than 95% by placing the cultures in 10% lipoprotein-poor serum rather than 10% FCS during the exposure to dBcAMP. Mevinolin (10 microM), a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme of the sterol biosynthetic pathway, completely inhibited the induction of CNP by dBcAMP, while not affecting either the accumulation of cellular protein per flask or rate of protein synthesis. Simultaneous addition of mevalonate (20 mM) prevented the inhibition of the induction of CNP by mevinolin. However, simultaneous addition of low-density lipoprotein sufficient to increase the cholesterol content of the medium 80-fold failed to correct mevinolin's inhibition of the induction of CNP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oligodendroglial differentiation in glial primary cultures: requirement for mevalonate. 303 49

The adrenal medulla contains an enzyme which catalyzes the hydrolysis of 2',3'-cAMP to 2'-AMP. For the parameters which have been examined, the adrenal medulla 2',3'-cAMP phosphodiesterase appears to be similar to brain 2',3'-cyclic nucleotide 3'-phosphodiesterase (also commonly referred to as CNPase). The apparent Km of the adrenal medulla CNPase for 2',3'-cAMP is 0.88 mM. The enzyme activity is unaltered by either EDTA, MgCl2 or CaCl2 in the presence or absence of calmodulin. The apparent molecular weight is 102,500 daltons. The function of the enzyme in either the brain or the adrenal medulla is, at the present time, unknown.
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PMID:Identification of 2',3'-cyclic nucleotide 3'-phosphodiesterase in bovine adrenal medulla. 370 18

Enzyme induction by hydrocortisone (HC) and dibutyryl cyclic AMP (dbcAMP) was studied in C6 rat glioma cells, FU5AH rat hepatoma cells, and five C6 x FU5AH hybrids. Hormone responsive enzymes from both parental lines were studied, including: tyrosine aminotransferase (TAT), alanine aminotransferase (AAT), glycerol phosphate dehydrogenase (GPDH), lactate dehydrogenase (LDH), and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP). There was no overall dominance of one parental phenotype over the other in expression of uninduced or induced enzyme activity after fusion, and the hybrids possessed some enzymatic properties characteristic of both parents. GPDH was induced by dbcAMP in all five hybrids, and TAT was induced by dbcAMP in four of the hybrids, although neither of these enzymes were induced by dbcAMP in the parents. Furthermore, synergistic induction of these enzymes by HC and dbcAMP was observed in the hybrids but not in the parents. These hybrids provide a model system to study hormone interaction in enzyme induction.
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PMID:Synergistic enzyme induction by glucocorticoids and cyclic AMP observed in glioma x hepatoma cell hybrids but not in their parents. 614 8

The enzyme, 2':3'-cyclic nucleotide 3'-phosphodiesterase (2':3'-cNMP-3'-ase) has been used as a marker in the nervous system for the presence of myelin membrane or myelin-producing glial cells. In this study, goldfish and bovine neural retinas are found to have high levels of such a diesterase activity. Analysis of retinal tissue incubated with 2':3'-cAMP shows only 2'-AMP as the reaction product, indicating the selective hydrolysis of the cyclic nucleotide. Microdissection of the goldfish retina demonstrates the highest 2':3'-cNMP-3'-ase activity in the region of the photoreceptors. A fraction enriched in bovine rod outer segments has about a 5-fold increase in specific enzyme activity when compared to whole retina preparations. These data suggest that 2':3'-cNMP-3'-ase is either closely associated with or is an intrinsic feature of vertebrate photoreceptor elements. The retina, which contains this enzyme, may serve as a model to investigate the influence of 2':3'-cyclic nucleotides on a function of the nervous system.
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PMID:Identification of 2':3'-cyclic nucleotide 3'-phosphodiesterase in the vertebrate retina. 624 10

A novel method has been developed for the preparation of nearly pure separate cultures of astrocytes and oligodendrocytes. The method is based on (a) the absence of viable neurons in cultures prepared from postnatal rat cerebra, (b) the stratification of astrocytes and oligodendrocytes in culture, and (c) the selective detachment of the overlying oligodendrocytes when exposed to sheer forces generated by shaking the cultures on an orbital shaker for 15--18 h at 37 degrees C. Preparations appear greater than 98% pure and contain approximately 1-2 x 10(7) viable cells (20--40 mg of cell protein). Three methods were used to characterize these two culture t ypes. First, electron microscopic examination was used to identify the cells in each preparation (mixed and separated cultures of astrocytes and oligodendrocytes) and to assess the purity of each preparation. Second, two oligodendroglial cell markers, 2',3'-cyclic nucleotide 3'-phosphohydrolase (EC 3.1.4.37) and glycerol phosphate dehydrogenase (EC 1.1.1.8) were monitored. Third, the regulation of cyclic AMP accumulation in each culture type was examined. In addition to these studies, we examined the influence of brain extract and dibutyryl cAMP on the gross morphology and ultrastructure of each preparation. These agents induced astroglial process formation without any apparent morphological effect on oligodendrocytes. Collectively, the results indicate that essentially pure cultures of astrocytes and of oligodendrocytes can be prepared and maintained. These preparations should significantly aid in efforts to examine the biochemistry, physiology, and pharmacology of these two major classes of central nervous system cells.
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PMID:Preparation of separate astroglial and oligodendroglial cell cultures from rat cerebral tissue. 624 68

2',3'-Cyclic nucleotide 3'-phosphodiesterase (CNP, EC 3.1.4.37) has been isolated from rat brain myelin by chromatography on successive columns of phenyl-Sepharose CL-4B, CM-Sepharose CL-6B, and 8-(6-aminohexyl) amino-2'AMP-Sepharose 4B. From 15 g of rat brain, approximately 400 micrograms of pure CNP was obtained, with a specific activity of 1,200 (2',3'-cyclic AMP) units/mg protein. The Km of the rat enzyme was 3.7 mM, using 2',3'-cAMP as the substrate. Isoelectric focusing of the enzyme indicated a broad isoelectric range of 8.5-9.0. On SDS polyacrylamide gels, rat CNP appears as two protein bands of approximately 48,000 and 50,000 M.W., with an upper band intensity of about 1/10 that of the lower band. The relative intensities of the bands for CNP and the molecular weights correspond to the Wolfgram proteins W1 and W2 described by other investigators. The amino acid analysis of the purified rat enzyme compared favorably with reported determinations for the bovine enzyme and also with reported values for the rat Wolfgram proteins W1 and W2.
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PMID:Purification of rat 2',3'-cyclic nucleotide 3'-phosphodiesterase. 625 58

1. A spectrophotometric assay of 2':3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37) based on the use of an acid-base indicator and a buffer having identical pKa values is described. The assay is simple and rapid; it was particularly convenient for monitoring the enzyme activity at various stages of purification. 2. Several proteinases were examined for their ability to solubilize 2':3'-cyclic nucleotide 3'-phosphodiesterase from delipidated brain white matter. Trypsin (EC 3.4.21.4) and elastase (EC 3.4.21.11) appeared to be more effective than the other proteinases examined. Trypsin, however, caused inactivation; elastase was therefore chosen to solubilize 2':3'-cyclic nucleotide 3'-phosphodiesterase. When a partially purified preparation of 2':3'-cyclic nucleotide 3'-phosphodiesterase was treated with elastase, 2':3'-cyclic nucleotide 3'-phosphodiesterase was solubilized nearly quantitatively. Elastatinal, a specific inhibitor of elastase, specifically inhibited the solubilization with elastase. 3. 2':3'-cyclic nucleotide 3'-phosphodiesterase was purified from bovine brain white matter by: (i) delipidation; (ii) solubilization with hexadecyltrimethylammonium bromide; (iii) gel chromatography on Sepharose; (iv) ethanol precipitation and resolubilization by digestion with elastase; (v) chromatography on DEAE-Sephadex; (vi) affinity chromatography on 8-(6-aminohexyl)amino-2'-AMP-Sepharose. 4. The purified enzyme migrated as a single protein band on polyacrylamide-gel electrophoresis at pH 4.3 and on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis; the estimated mol.wt. in the latter electrophoresis was 27000-31000. Gel filtration of the purified enzyme through Sephadex G-150 indicated a mol.wt. of 31000. Therefore the purified enzyme is a monomer protein with a mol.wt. of approx. 30000.
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PMID:Spectrophotometric assay, solubilization and purification of brain 2':3'-cyclic nucleotide 3'-phosphodiesterase. 625 86


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