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:3.1.4.37 (CNPase)
539 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Membrane sheets elaborated by cultured murine oligodendroglia provide a unique system for examining associations between myelin proteins and cytoskeletal elements. Interactions can be observed and manipulated more readily than in the multilamellar myelin membrane in vivo. Immunocytochemical staining of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) shows that it is distributed diffusely in some regions of membrane sheets, but colocalized with tubulin in lacy networks and major veins in other regions. Staining with phalloidin also reveals two distributions of F-actin: 1) small aggregates within the diffuse CNPase regions and 2) filaments colocalized with tubulin and CNPase in the lacy networks and veins. Application of colchicine at 10 micrograms/ml for 4 hr disrupts microtubular structures in the lacy network, while those in major veins remain intact. This suggests that microtubules in the lacy network are treadmilling more rapidly than those in the major veins. The distribution of CNPase and F-actin is not altered under these conditions. In contrast, cytochalasin B disrupts F-actin, microtubules, and CNPase in the lacy networks, indicating that cross-linking between these three proteins is disrupted. Both colchicine and cytochalasin B cause fusion of myelin basic protein (MBP) domains in membrane sheets. This appears to be a consequence of disruption of microtubules in the lacy networks, which normally outline the MBP domains. In summary, these results provide evidence for 1) direct association of CNPase with F-actin and tubulin in cytoskeletal structures and 2) organization of MBP into domains via association with microtubules in the lacy networks.
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PMID:Organization of oligodendroglial membrane sheets. I: Association of myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphohydrolase with cytoskeleton. 247 63

The nervous system of a mouse mutant characterized by a carbonic anhydrase II (CA II) deficiency was examined with light and electron microscopy and with immunocytochemistry using different glial cell markers. No major morphologic abnormalities at either the cellular or subcellular level are detectable in the brains of CAII-deficient mice, even though CAII is the main isozyme of CA in the brain. The oligodendrocytes, which characteristically express high levels of CA II, do not exhibit signs of degeneration or abnormalities even in 1-year-old CA II-deficient mice. Similarly, neurons and astrocytes have a normal structure and distribution. Oligodendrocytes show a normal staining pattern and distribution for galactocerebroside (GC), 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), and myelin basic protein (MBP). Astrocytes have a normal morphology and distribution when stained for GFAP and S100 protein. The lack of major degeneration in the brain due to a CA II deficiency suggests these mice utilize other enzymatic or physiological pathways to compensate for the enzyme absence.
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PMID:Oligodendrocytes express a normal phenotype in carbonic anhydrase II-deficient mice. 250 36

We have hypothesized that oligodendrocyte (OL) surface glycolipids, specifically galactocerebroside and sulfatide, play a role in the regulation of OL development by acting as sensors/transmitters of environment information. In support of this hypothesis we report here a reversible inhibition of OL progenitor cell differentiation by a monoclonal antibody [Ranscht mAb (R-mAb); Ranscht, B., Clapshaw, P. A. & Seifert, W. (1982) Proc. Natl. Acad. Sci. USA 79, 2709-2713] that reacts with these glycolipids. When isolated OL progenitors or mixed primary cultures are grown in the presence of the antibody, myelinogenic development is blocked in a dose-dependent manner at concentrations as low as 2 micrograms of IgG per ml. The inhibited cells express the OL progenitor markers O4 and vimentin but are negative for galactosylcerebroside, sulfatide, 2',3'-cyclic nucleotide 3'-phosphohydrolase, myelin basic protein, and myelin basic protein RNA expression. In contrast, the levels of total cellular protein and the expression of astrocytic glial fibrillary acidic protein in mixed cultures are not affected. Antibody-blocked cells have a distinctive morphology in which long, sparsely branched processes emanate from round cell bodies. Upon removing the perturbing antibody, the cells rapidly resume differentiation. Reverted mixed primary cultures, in which OL progenitors of several sequential developmental stages are present at the time of plating, differentiate more rapidly than control cultures, suggesting that the antibody-induced block results in a synchronization of developmental progression along the OL lineage by accumulating cells at the inhibition point. However, the normal temporal sequence of marker expression is maintained. Control studies with several other antibodies recognizing OL cell surface antigens, including HNK-1, neural cellular adhesion molecule (N-CAM), 1A9, anticholesterol, and O1, did not inhibit development. Since the inhibition occurs in highly enriched populations of OL progenitors, the inhibition does not involve cell-cell interactions between OLs and other cell types but concerns interactions of OLs with themselves, soluble factors, or OL extracellular matrix molecules and adhesion factors that provide essential environmental signals required for normal myelinogenic development.
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PMID:Reversible inhibition of oligodendrocyte progenitor differentiation by a monoclonal antibody against surface galactolipids. 266 57

Extraction of rat brain myelin in a buffer containing Triton X-100 yielded a soluble fraction and an insoluble residue that was enriched in cytoskeletal elements. Immunoblot analysis of the detergent-soluble fraction and the insoluble cytoskeletal residue showed that all of the tubulin and more than half of the actin were found within the cytoskeletal fraction. The distribution of myelin-specific proteins was also examined, and revealed that 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) I and most of the myelin basic proteins (MBPs) were equally distributed between both fractions. By contrast, the large MBP (21.5 kDa) and CNPase II (50 kDa) were observed to partition almost entirely with the cytoskeletal fraction. Proteolipid protein was found predominantly in the detergent-soluble fraction, as was DM-20 protein. Analysis of the cytoskeletal fraction by sucrose-density-gradient centrifugation demonstrated that a distinct subset of lipids was tightly bound to the cytoskeletal protein residue. The cytoskeleton-associated lipid was considerably enriched in cerebroside and sphingomyelin by comparison with total myelin lipids. These results indicate that a cytoskeletal matrix is associated with multilamellar myelin, and suggest that this structure may play a fundamental role in myelinogenesis.
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PMID:Characterization of a cytoskeletal matrix associated with myelin from rat brain. 276 98

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

Fresh lesions in the brain and spinal cord of patients with multiple sclerosis who died shortly after the onset of symptoms were examined immunocytochemically for myelin and oligodendrocyte antigens that are known to be sequentially expressed during normal development. Cells with oligodendrocyte-like morphology that appear in large numbers throughout fresh lesions after acute myelin breakdown and before new myelin formation were found to express galactocerebroside, carbonic anhydrase, and 2',3'-cyclic nucleotide 3'-phosphohydrolase but not myelin-associated glycoprotein or myelin basic protein. They also exhibit intense surface reactivity for a carbohydrate epitope associated with the family of cell adhesion molecules recognized by the monoclonal antibody HNK-1. With the onset of remyelination and the appearance of myelin-associated glycoprotein, myelin basic proteins, CNP, and the HNK-1 epitope is newly formed myelin sheaths, perikaryon CNP and HNK-1 reactivity diminished. A possible oligodendrocyte precursor cell in the form of a large HNK-1 positive glial fibrillary acidic protein negative glial cell was observed among interfascicular oligodendrocytes in white matter bordering these hypercellular plaques. Because a similar progression in the expression of CNP and the HNK-1 epitope occurs during normal oligodendrocyte differentiation, these observations are additional evidence that extensive oligodendrocyte regeneration occurs in some plaques early in the course of the disease. The finding of large numbers of immature oligodendrocytes, presumably expressing many developmentally restricted antigens not normally present in the mature nervous system, in plaques at a particular stage in their evolution may be important in understanding why remyelination eventually fails in multiple sclerosis.
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PMID:Multiple sclerosis. Oligodendrocyte proliferation and differentiation in fresh lesions. 281 Dec 98

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

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

In this paper, the characterization of four human malignant glioma cell lines is described. The four lines are positive for glial fibrillary acidic protein (GFAP) in variable amounts. One of them, LN 992, is positive for S-100 protein. Myelin basic protein could not be detected in any of the four lines. The four lines had high levels of CNPase activity. The karyotype shows polyploidy for all lines, with modal numbers ranging from 80 to 120 and various numbers of marker chromosomes. Particular attention has been paid to the surface phenotype and a panel of three antiglioma monoclonal antibodies (Mabs), five antimelanoma Mabs, one anti-CALLA Mab, and two anti-HLA-DR Mabs has been used in an antibody-binding radioimmunoassay for the four cell lines. Lines LN 215 and LN 235 are positive with two antiglioma Mabs, LN 992 is negative. The four lines are positive with all five antimelanoma Mabs, except for LN 992 which ist negative with Mab D5. LN 992 and LN 215 are positive with the anti-CALLA Mab N2A12. LN 308 and LN 992 are positive with anti-HLA-DR Mab D4-22. There was no correlation between the in vitro morphology of the lines and the expression of the various biochemical or surface markers. These results stress the heterogeneity of the phenotype of human malignant glioma lines. These lines will be useful tools for further immunologic studies.
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PMID:Characterization of four human malignant glioma cell lines. 299 Jan 47

The enzyme 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) is one of the important markers for myelin synthesis or demyelination. We measured the CNPase activities in the visual pathway tissues of Lewis strain rats with experimental allergic encephalomyelitis (EAE) induced by inoculation of myelin basic protein from the brain. The enzyme activities in the retina, optic nerve, optic chiasma and lateral geniculate body were reduced to about 50-80% of that of controls at 15 days after myelin basic protein inoculation when symptoms of EAE were most severe. However, the activities recovered at 19 days except in the retina when the symptoms of EAE disappeared. Furthermore, the activities of the optic nerve and chiasma increased to a level higher than that of the controls at this time. By histopathological study, infiltration of inflammatory cells and focal demyelination were found in the optic nerve and lumbar spinal cord at 15 days after myelin basic protein inoculation. It was considered that the reduction of CNPase activity and its recovery and increase reflect demyelination and activation of oligodendroglia for remyelination, respectively.
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PMID:2',3'-cyclic nucleotide 3'-phosphohydrolase activity in rat visual pathways with experimental allergic encephalomyelitis. 301 90


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