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)

A procedure is described for isolating two membrane fractions from rabbit spinal-cord white matter enriched with 5'-nucleotidase, a nonspecific plasma membrane marker, 2',3'-cyclic nucleotide phosphohydrolase, an oligodendroglial plasma membrane marker, and acetylcholinesterase, an axonal plasma membrane marker. While the two membrane fractions exhibited similar enrichments with respect to cyclic nucleotide phosphohydrolase, enrichments of 5'-nucleotidase and acetylcholinesterase were significantly greater in the heavier membrane fraction. Selected enzyme markers for cyto- and mitochondrial membranes were not detected. Moreover, gray matter did not yield homologous membrane fractions in the gradient when subjected to the identical procedure, indicating that the two membrane fractions were unique to white matter. While electronmicroscopic examination revealed that both membrane fractions were comtaminated with myelin, the heavier fraction was least contaminated and exhibited a fair degree of homogeneity with respect to single membrane vesicular profiles. It was concluded that both membrane fractions were enriched with oligodendroglial and axonal plasma membranes, with the heavier fraction containing significantly more axolemma.
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PMID:Isolation of non-myelin plasma membranes unique to white matter. 19 99

Schwann cells, on receiving the correct signal, will encircle an axon and wrap it with a myelin sheath. To begin examining some of the mechanisms underlying the process of myelination in vitro, we isolated Schwann cells from the sciatic nerves of neonatal rats and generated large cell populations with cholera toxin. The immunological and biochemical properties of these secondary Schwann cells were characterized after five to seven passages in the absence of axonal contact. These cells continued to express antigens found in both myelinating (P0 and 2',3'-cyclic nucleotide phosphohydrolase) and nonmyelinating cells in vivo (A5E3 and glial fibrillary acidic protein) in addition to the markers common to both types of cells (Ran-1, 217c, S-100, and laminin). Biochemical analyses showed that these cells synthesize the very-long-chain fatty acids (22-26 carbon atoms) found in myelin membranes. Moreover, the enzymes required for the synthesis of myelin glycolipids (including sphingosine acyltransferase, UDP-galactose:ceramide galactosyltransferase, and cerebroside sulfotransferase) were still active, and metabolic labeling studies showed that galactocerebroside and sulfatide were synthesized even though the galactocerebroside pool was insufficient to be detected by immunostaining. Secondary Schwann cells also synthesized four species of myelin basic protein and the major structural glycoprotein in myelin, P0. The pathway necessary for glycosylation of P0 protein remained active, and an analysis of the oligosaccharide chain revealed that approximately 70% was processed to a complex form. In summary, we found that secondary Schwann cells still express most of the immunological markers of differentiated cells and continue to synthesize low levels of myelin components. Therefore, Schwann cells do not dedifferentiate in culture, as previously believed.
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PMID:Evidence that secondary rat Schwann cells in culture maintain their differentiated phenotype. 169 82

Schwann cells are responsible for the maintenance of the peripheral myelin sheath and neurotoxic insult directed against these cells can result in demyelination with a concomitant loss of neural function. We have utilized several in vitro techniques to investigate the effects of neurotoxins on the complex interactions between SC and axons. SC may be isolated from fresh neonatal sciatic nerves and used to examine the effect of neurotoxins on the axonal membrane induction of SC proliferation and specific myelin protein mRNA expression. We have recently devised a method to obtain SC from frozen sciatic nerves. This method allows pooling of neonatal nerves to generate enough cells for subsequent study. We have also transfected primary Schwann cells with a plasmid containing the large T antigen to obtain a SC line suitable for neurotoxicology studies. The functional status of cultured SC may also be studied via expression of SC specific antigens such as glial fibrillary acidic protein, CNPase, S100, laminin, P0 and myelin basic protein. We also propose culturing SC with dorsal root ganglion neurons to investigate the effect of neurotoxins on all stages of SC maturation, from proliferation to the in vitro synthesis of a compact myelin sheath. These strategies will allow us to investigate the cellular mechanisms of neurotoxicity in the PNS.
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PMID:In vitro use of Schwann cells to elucidate neurotoxic injury. 174 36

We monitored biosynthetic activity of optic tract glia during regeneration of retinal ganglion cell axons in the goldfish and found that the greatest level of incorporated [3H]thymidine and [3H]leucine occurred in glia by 10-15 days after axotomy. During this period there was a marked increase in the number of oligodendroglia and multipotential glia near the site of injury with no change occurring in the astroglial population. Electron microscopic autoradiography showed that oligodendroglia and multipotential cells incorporated 5-7-fold more thymidine than did cells of intact control preparations. Though all glial cell types incorporated more [3H]leucine during axonal regeneration, oligodendroglia and multipotential cells together accounted for more than 90% of measured radioactivity. In order to characterize glial-stimulating events specific to axonal regeneration, we produced axonal degeneration in the optic tract by removal of the retina. Optic tract glia during axonal degeneration incorporated less amino acid when compared to glia associated with regenerating axons. The degenerating optic tract also had less 2',3'-cyclic nucleotide 3'-phosphohydrolase, an enzyme produced by oligodendroglia, than that found in the regenerating visual system. Our results suggest that in response to ganglion cell axotomy oligodendroglia and multipotential glia of the goldfish optic tract proliferate. Moreover, regenerating axons provide one type of stimulant for glial protein biosynthesis.
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PMID:The response of optic tract glia during regeneration of the goldfish visual system. I. Biosynthetic activity within different glial populations after transection of retinal ganglion cell axons. 299

Experimental spinal cord trauma was produced in rats by dropping a 10-g weight from a height of 30 cm upon exposed spinal cord. The histological lesion consisted of edema, necrosis, and hemorrhage. The fine structure of the early traumatic lesion (4 to 12 hours) included granular dissolution of axons and a characteristic vesiculation of myelin. The predominant ultrastructural features of older lesions (12 to 72 hours) were intra-axonal calcification and lipid-laden macrophages. The yield of myelin and the activity of adenosine 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) were reduced by approximately 15% at 4 hours and by 60% at 72 hours. Losses in all myelin proteins were observed, but were most severe and occurred earliest in the basic proteins. The ultrastructural and biochemical alterations observed in this study indicate that proteinase activity is increased and may be partially responsible for the traumatic myelinolysis in experimental spinal cord trauma.
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PMID:The effects of spinal cord trauma on myelin. 624 91

Four enzymes related to specific cell functions were assayed in rat sciatic nerve injury by crush (cr) or crush and ligation (cr-lig) after 2, 7, and 15 days in situ. Enzyme activities in segments of sciatic nerve proximal and distal to the injury were compared to those in corresponding segments of the contralateral nerve. Choline acetyltransferase (CAT) activity in the distal portion decreased by 65% for cr and almost to zero for cr-lig by day 7, while in the proximal portions CAT decreased to 70% of control values by 7 days and to 50% at 15 days after cr-lig. The activity of the Schwann cell-myelin-associated enzyme 2',3'-cyclic nucleotide phosphohydrolase (CNP) decreased slowly distal to the injury. Distal to both types of injury the lysosomal enzyme beta-glucuronidase (GLR) increased six- to eightfold by 15 days. Proximal to injury GLR also increased (P cr X 2.5, P cr-lig X 5) but the peak proximally was attained by day 7. Despite interruption of axonally transported enzymes, the activities of the metabolic enzyme creatine kinase (CK) increased distal to injury apparently reflecting changes in the functions of the Schwann cells. The loss of metabolic enzymes from the axonal compartment may be completely obscured by reciprocal changes in the non-neuronal compartments if the activity is present in both compartments.
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PMID:Enzyme changes in axon, myelin, and Schwann cells in injured sciatic nerve. 631 Jan 39

A comprehensive biochemical, immunological and histological study was undertaken during different stages of experimental allergic encephalomyelitis (EAE). Wistar rats with EAE induced by sensitization with bovine myelin showed a maximum decrease of body weight 14-16 days post-inoculation (dpi), coincident with the appearance of the paralysis symptom (acute period). Quantitation of some brain components indicated a temporal dissociation among the alterations observed. The higher diminution of myelin basic protein (MBP) occurred at 6 dpi and then increased to reach 21 dpi, a normal value. Also, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase was reduced by 40% with respect to control animals only at 6 dpi. The total lipid content was normal; however, among the individual lipids, sulfatides were principally degraded during the acute stage but the amount of cerebrosides was decreased during the recovery period (29-40 dpi). Free cholesterol was similar in both groups of animals, whereas cholesterol esters were detected in EAE animals from 14 to 40 dpi. Central nervous system meningeal and parenchymal infiltration with mononuclear cells was recognized principally at 14 dpi, but some of cells were still present at 40 dpi. Deposits of immunoglobulins in the infiltrated regions as well as in spinal cord motor neurons were observed among 14-29 dpi. Total circulating antibodies to MBP began to increase at 14 dpi, reaching a plateau at 21 dpi and then maintaining this value until 40 dpi. However, the population of anti-MBP antibodies that also recognizes the neuronal protein synapsin was only present at 14 dpi. The present results suggest that the neurological symptoms can be related to some early changes in the myelin membrane followed by alterations involving neuronal structures. The existence of immunological factors against some epitopes in MBP that also recognize a synaptosomal protein might account, at least in part, for the axonal damage and disruption of the normal interneuronal activity in EAE and lead together with the alterations in some specific myelin constituents and the concomitant CNS inflammatory process to the observed hindlimb paralysis.
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PMID:Time course of biochemical and immunohistological alterations during experimental allergic encephalomyelitis. 911 27

A human recombinant monoclonal antibody to herpes simplex virus (HSV) glycoprotein D labeled with the fluorescent dye Cy5 was administered to mice infected in the cornea with HSV type 1 (HSV-1). The distribution of such antibody in the corneas and trigeminal ganglia of the mice was then investigated by confocal microscopy. The antibody was detected on HSV-infected nerve fibers in the cornea--identified by colocalization with HSV antigens and the neuritic markers neurofilament, GAP-43, synapsin-1, and CNPase--and on the perikarya of sensory neurons in the HSV-1-infected neurons in ipsilateral trigeminal ganglia. Antibodies have been shown to be effective against many neurotropic viruses, often in the absence of obvious cell damage. Observations from experimental HSV infections suggest that antibodies could act in part by interfering with virus expression in the ganglia and/or with axonal spread. The present results provide morphological evidence of the localization of antiviral antibodies at anatomical sites relevant to such putative antibody-mediated protective actions and suggest that viral glycoproteins are accessible to antibodies on infected nerve fibers and sensory neurons.
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PMID:Localization of a passively transferred human recombinant monoclonal antibody to herpes simplex virus glycoprotein D to infected nerve fibers and sensory neurons in vivo. 1048 37

Spinal cord white matter is susceptible to AMPA/kainate (KA)-type glutamate receptor-mediated excitotoxicity. To understand this vulnerability, it is important to characterize the distribution of AMPA/KA receptor subunits in this tissue. Using immunohistochemistry and laser confocal microscopy, we studied the expression sites of AMPA/KA receptor subunits in mouse spinal cord. The white matter showed consistent immunoreactivity for AMPA receptor subunit GluR2/3 and KA receptor subunits GluR6/7 and KA2. In contrast, antibodies against GluR1, GluR2, GluR4 (AMPA), and GluR5 (KA) subunits showed only weak and occasional labeling of white matter. However, gray matter neurons did express GluR1 and GluR2, as well as GluR2/3. The white matter astrocytes were GluR2/3 and GluR6/7 immunopositive, while the gray matter astrocytes displayed primarily GluR6/7. Both exclusively and abundantly, KA2 labeled oligodendrocytes and myelin, identified by CNPase expression. Interestingly, myelin basic protein, another myelin marker, showed less correlation with KA2 expression, placing KA2 at specific CNPase-containing subdomains. Focal points of dense KA2 labeling showed colocalization with limited, but distinct, axonal regions. These regions were identified as nodes of Ranvier by coexpressing the nodal marker, ankyrin G. Overall, axonal tracts showed little, if any, AMPA/KA receptor expression. The proximity of oligodendrocytic KA2 to the axonal node and the paucity of axonal AMPA/kainate receptor expression suggest that excitotoxic axonal damage may be secondary and, possibly, mediated by oligodendrocytes. Our data demonstrate differential expression of glutamate AMPA and KA receptor subunits in mouse spinal cord white matter and point to astrocytes and oligodendrocytes as potential targets for pharmacological intervention in white matter glutamate excitotoxicity.
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PMID:AMPA/kainate receptors in mouse spinal cord cell-specific display of receptor subunits by oligodendrocytes and astrocytes and at the nodes of Ranvier. 1259 33

Periaxonal glia play an important role in maintaining axonal function in white matter. However, little is known about the changes that occur in glial cells in situ immediately after traumatic injury. We used fluo-3 and confocal microscopy to examine the effects of localized (<0.5 mm) mechanical trauma on intracellular calcium (Ca(i)(2+)) levels in glial cells in a mature rat spinal cord white matter preparation in vitro. At the injury site, the glial Ca(i)(2+) signal increased by 300-400% within 5 min and then irreversibly declined indicating cell lysis and death. In glial cells at sites adjacent to the injury (1.5-2 mm from epicenter), Ca(i)(2+) levels peaked at 10-15 min, and thereafter declined but remained significantly above rest levels. At distal sites (6-9 mm), Ca(i)(2+) levels rose and declined even slower, peaking at 80-90 min. Injury in zero calcium dampened Ca(i)(2+) responses, indicating a role for calcium influx in the generation and propagation of the injury-induced Ca(i)(2+) signal. By 50-80 min post-injury, surviving glial cells demonstrated an enhanced ability to withstand supraphysiological Ca(i)(2+) loads induced by the calcium ionophore A-23187. Glial fibrillary acidic protein (GFAP) and CNPase immunolabeling determined that the glial cells imaged with fluo-3 included both astrocytes and oligodendrocytes. These data provide the first direct evidence that the effects of localized mechanical trauma include a glial calcium signal that can spread along white matter tracts for up to 9 mm within less than 3 h. The results further show that trauma can enhance calcium regulation in surviving glial cells in the acute post-injury period.
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PMID:Confocal imaging of changes in glial calcium dynamics and homeostasis after mechanical injury in rat spinal cord white matter. 1500 75


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