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)

The role of N-linked glycoproteins in the development of oligodendroglia has been studied in a culture system that initially contains the progenitor cell for oligodendroglia and type 2 astrocytes. The progenitor cells, derived from mixed glial primary cultures of newborn rat cerebrum, were studied under culture conditions that we have shown previously to induce oligodendroglial differentiation. Castanospermine was used to inhibit processing of N-linked glycoproteins by its inhibitory action on glucosidase I, the enzyme responsible for the initial trimming of glucose residues from the glucosylated high mannose core oligosaccharide derived from the dolichol pathway. Exposure to castanospermine had no effect on the initial commitment of the progenitors to oligodendroglial differentiation, i.e. 95% of both control and castanospermine-treated cells became galactocerebroside (GC) positive. However, the developmental inductions of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and glycerol-3-phosphate dehydrogenase (GPDH) and the elaboration of a network of fine interconnecting processes were prevented by the castanospermine exposure. No effect of castanospermine on cell number was observed. A major effect of the inhibitor on glycoprotein processing was manifested by an accumulation of high mannose glycoproteins, of abnormal oligosaccharide structure, compatible with the inhibition of glucosidase I.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glycoprotein processing is required for completion but not initiation of oligodendroglial differentiation from its bipotential progenitor cell. 128 24

Mixed glial primary cultures derived from neonatal rat brain were used to isolate the progenitor glial cell with the capacity to differentiate into oligodendroglia or type 2 astrocytes depending on the culture medium. Subcultures composed primarily of this progenitor were utilized, first, to study the regulation of oligodendroglial differentiation by two factors added to chemically defined medium (CDM), i.e. boiled fetal calf serum (FCS) and cellular extract of type 1 astrocytes, and, second, to devise culture conditions that would cause the progenitor cells to differentiate virtually exclusively along oligodendroglial lines (judged by immunologically identified expression of galactocerebroside; GC) and with high specific and total activity of the oligodendroglial enzymes, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and glycerol-3-phosphate dehydrogenase (GPDH). Addition of untreated FCS to CDM of the progenitors resulted in 6 days in richly cellular, mixed glial cultures composed of slightly more GFAP-positive astrocytes than oligodendroglia. Addition of boiled FCS to CDM of the progenitors resulted in 6 days in cultures composed almost exclusively (95%) of GC-positive cells and with high specific activity of CNP. This effect of boiled serum, compared to untreated serum, was related to virtual elimination of astrocytes, in the presence of continued differentiation to GC-positive oligodendroglia. Addition of type 1 astrocyte extract as well as boiled FCS to CDM was necessary to generate high specific activity of GPDH. Additionally, the total number of oligodendroglia increased 2-fold when astrocyte extract as well as boiled FCS was added to the CDM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Establishment of a culture system for the study of oligodendroglial development: complementary effects of boiled serum and astrocyte extract. 128 25

Primary cultures of cerebral glia derived from neonatal rat brain were utilized to determine whether specific glycoproteins are involved in oligodendroglial and astrocytic differentiation. Specific emphasis was placed on the oligosaccharide portion of glycoproteins, and inhibitors of glycoprotein processing were studied. Castanospermine, an inhibitor of glucosidase I, and thereby formation of both complex glycoproteins and high mannose glycoproteins, and deoxymannojirimycin (DMM), an inhibitor of mannosidase I and thereby formation of complex glycoproteins, were utilized. Castanospermine exposure prevented the developmental inductions of the two oligodendroglial markers, 2',3'-cyclic nucleotide 3'-phosphohydrolase and glycerol-3-phosphate dehydrogenase. The effect of castanospermine on oligodendroglial differentiation was reversible. In contrast, castanospermine had no effect on the developmental inductions of the two astrocytic markers, glutamine synthetase and lactate dehydrogenase. DMM exposure had no effect on either oligodendroglial or astrocytic differentiation. Although both inhibitors caused a marked decrease in the formation of complex glycoproteins and an increase in high mannose structures, the oligosaccharide composition of these high mannose structures differed markedly. Castanospermine caused an increase in 'abnormal', apparently glucosylated high mannose structures and a decrease in all other 'normal' high mannose oligosaccharides, whereas DMM caused an increase in most high mannose structures, especially those migrating in the region of the Man7GlcNAc standard. The data indicate that oligodendroglial differentiation requires specific N-linked oligosaccharides, probably principally of the high mannose type, and that astrocytic differentiation can proceed normally despite marked alterations in both complex and high mannose glycoproteins.
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PMID:Specific N-linked oligosaccharides are required for oligodendroglial differentiation but probably not for astrocytic differentiation. 213 78

The brains from 1-week-old rat pups were used to prepare cultures of glial cells. After 24 hr in culture the cells were changed to a chemically defined serum-free medium (CDM). We have used antibodies against gangliosides (monoclonals A2B5 and LB1) and against galactocerebrosides to monitor the influence of insulin on the development of oligodendrocytes from precursor cells. In these oligodendrocyte-enriched cultures we investigated the influence of insulin and IGF-I on the activity of the marker enzymes 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) and glycerol-3-phosphate dehydrogenase (G3PDH), and on lipid metabolism. 1) Incorporation of [35S] sulfate into sulfolipids was stimulated by insulin (optimal concentration 100 nM). A sharp peak in sulfolipid synthesis was seen at day 5-6 in culture. 2) Insulin stimulated the expression of CNPase and G3PDH in culture. 3) The stimulating effect of insulin on sulfolipid synthesis, CNPase, and G3PDH activity was mimicked by IGF-I (13 nM). 4) The incorporation of [35S] into sulfolipids and [2-3H]acetate into fatty acids and cholesterol was reversibly reduced by temporary omission of insulin from the medium. These results indicate that insulin and IGF-I stimulate the development of oligodendrocytes in our culture system and that insulin has a general anabolic effect on the lipid metabolism of the cells.
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PMID:Effects of insulin and insulin-like growth factor (IGF-I) on oligodendrocyte-enriched glial cultures. 283 44

The mixed glial system of primary cultures of cells dissociated from neonatal rat brain was utilized to study glial differentiation. The investigation was addressed specifically to the possibility of noncoordinate regulation of two manifestations of oligodendroglial differentiation, i.e., activities of glycerol-3-phosphate dehydrogenase (GPDH) and of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), as well as the effects of initial cell density on the time of onset and the intensity of expression of these aspects of oligodendroglial differentiation. Simultaneously, glutamine synthetase activity was studied to determine effects on astrocytic differentiation. GPDH exhibited a major developmental increase in specific activity between 20 and 32 days in culture. However, CNP activity exhibited a major developmental increase that commenced approximately 2 weeks earlier. The onset of these expressions of oligodendroglial differentiation was not affected by such environmental factors as initial cell density. However, the intensity of expression of the temporally separate increases in GPDH and CNP activities was markedly density-dependent. The highest activities were attained in cultures plated at the lowest cell densities. The astrocytic enzyme, glutamine synthetase, also exhibited a striking developmental increase (approximately tenfold between 13 and 30 days in culture), but initial cell density affected neither the time of onset nor the intensity of expression of this aspect of astrocytic differentiation. The data demonstrate a striking developmental increase in GPDH activity that is not coordinate with that in CNP. The noncoordinate manifestations of oligodendroglial differentiation commence as a function of time in culture, whereas the intensity of expression of this differentiation can be influenced by such environmental factors as initial cell density.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glial differentiation in dissociated cell cultures of neonatal rat brain: noncoordinate and density-dependent regulation of oligodendroglial enzymes. 287 Jan 95

A serumless, chemically defined medium has been developed for the culture of oligodendrocytes isolated from primary neonatal rat cerebral cultures. Combined together, insulin, transferrin, and fibroblast growth factor synergistically induced an essentially homogenous population (95-98%) of cells expressing glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) activity to undergo cell division. Proliferating cels were characterized by several criteria: (i) ultrastructural analysis by transmission electron microscopy identified the cell type as an oligodendrocyte; (ii) biochemical assays showed expression of three oligodendrocyte biochemical markers, induction of both glycerol phosphate dehydrogenase and lactate dehydrogenase (EC 1.1.1.27), and presence of 2',3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37); and (iii) immunocytochemical staining showed cultures to be 95-98% positive for glycerol phosphate dehydrogenase, 90% for myelin basic protein, 60-70% for galactocerebroside, and 70% for A2B5. Few cells (less than 5%) stained positive for glial fibrillary acidic protein, and none were detected positive for fibronectin.
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PMID:Characterization of cultured rat oligodendrocytes proliferating in a serum-free, chemically defined medium. 298 30

The enzymatic activities in post-mortem rat brain kept at 4 degrees C and at 25 degrees C were determined for a number of enzymes localized in specific cell types in the central nervous system. Choline acetyltransferase (CAT), glycerol-3-phosphate dehydrogenase (GPDH), glutamine synthetase (GS), lactate dehydrogenase (LDH) and 2',3'-cyclic nucleotide phosphohydrolase (CNPase) were found to be very stable at both 4 degrees C and 25 degrees C with only slight, if any, losses of activity being seen even at periods as long as 72 hr. Glutamic acid decarboxylase (GAD) activity was less stable than that of the other enzymes. In brains kept at 4 degrees C GAD activity was stable out to 24 hr after which it began to decline rapidly to 65% of control at 72 hr. In brains kept at 25 degrees C, GAD activity was stable for 6-8 hr and then began to steadily decline to 58% of control at 24 hr and 29% of control at 72 hr. Assuming that these enzymes have similar stabilities in post-mortem human brain, the effect of post-mortem delay in processing tissues may be of lesser significance than other factors with regard to the measured enzyme activities in human brain samples.
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PMID:Stability of neuronal and glial marker enzymes in post-mortem rat brain. 301 Jan 49

Cultures of glial cells were prepared from the brains of one-week-old rat pups. After one day in culture, serum was omitted from the medium and replaced by a combination of growth-stimulating hormones and other factors that enhanced the percentage of oligodendrocytes in the cultures. We investigated the effects of hydrocortisone on the development of oligodendrocytes, on the activities of oligodendrocyte-specific enzymes and on glucose- and lipid-metabolism of the glial cells. Hydrocortisone greatly enhanced the survival of glial cells in culture. The development of galactocerebroside-positive cells and the specific activity of 2',3'-cyclic-nucleotide 3'-phosphodiesterase were stimulated by 50 nM hydrocortisone, whereas these effects were partly reversed at higher concentrations of the hormone. The specific activity of glycerol-3-phosphate dehydrogenase was markedly stimulated by hydrocortisone; 1 microM or higher concentrations of hydrocortisone were required for an optimal effect. The consumption of glucose and the production of lactate were lowered by hydrocortisone whereas the oxidation of [6-14C]glucose to 14CO2 was not affected. Incorporation of [35S]sulfate into sulfolipids was greatly enhanced by hydrocortisone and [14C]incorporation from [1-14C]acetate into cholesterol and fatty acids was also stimulated but to a smaller extent. These results show that hydrocortisone exerts a general trophic function on glial cells in our culture system; enhances the ratio of oligodendrocytes over astrocytes, possibly by directing bipotential progenitor cells to develop into oligodendrocytes; specifically induces glycerol-3-phosphate dehydrogenase in oligodendrocytes.
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PMID:Hydrocortisone stimulates the development of oligodendrocytes in primary glial cultures and affects glucose metabolism and lipid synthesis in these cultures. 304 Jan 87

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

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


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