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J M Matthieu

Publications and source records attributed to J M Matthieu.

At least 73 records · Page 4Linked to original sources
PubMed1989

Myelin basic protein transcriptional activity in myelin-deficient mutant mice.

Myelin-deficient (mld) mice present two tandem myelin basic protein genes, with the upstream gene containing an inversion (Popko et al., Neuron 1: 221, 1988). Detailed analysis of the transcriptional activity of various regions of the gene showed that all portions of the MBP gene are transcribed in mld mice. Consequently, we propose that the low levels of MPB mRNA observed in mld mice are due to post-transcriptional events.

Animals↗
PubMed1988

Expression of myelin components in mouse Schwann cells in culture.

Mouse Schwann cells cultured in vitro are capable of expressing basal levels of the major myelin components P1, P2, P0, and galactocerebroside. Numerical counts of immunostained cultures indicated that between 22 and 40% of the cells are positive up to 21 days for all of the components indicated. Electrophoretic analysis of Schwann cells labeled with a 14C-amino acid mixture revealed the presence of proteins with relative mobilities identical to those of P0 and P1. Positive identification of the two proteins was indicated by immunoprecipitation of P1 and immunoblotting of P0. These data show that in the absence of neurites, Schwann cells in culture can express low levels of myelin characteristic components even in the absence of myelin assembly.

Amino Acids↗
PubMed1988

Developmental expression of glial fibrillary acidic protein and glutamine synthetase in serum-free aggregating cell cultures of fetal rat telencephalon.

Serum-free aggregating cell cultures of fetal rat telencephalon were examined by a combined biochemical and double-labeling immunocytochemical study for the developmental expression of glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS). It was found that these two astroglial markers are co-expressed at different developmental stages in vitro. During the phase of cellular maturation (i.e. between days 14 and 34), GFAP levels and GS activity increase rapidly and in parallel. At the same time, the number of immunoreactive cells increase while the long and thick processes staining in early cultures gradually disappear. The present results demonstrate that in this particular cell culture system only one type of astrocytes develops which expresses both GFAP and GS and which attains a relatively high degree of maturation.

Animals↗
PubMed1988

Immunocytochemical localization by electron microscopy of 2'3'-cyclic nucleotide 3'-phosphodiesterase in developing oligodendrocytes of normal and mutant brain.

Oligodendrocytes or their putative progenitors were the only cells found to be immunoreactive to polyclonal antisera against the enzyme 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in developing and mature brains of rats and mice, as visualized by light and electron microscopy. Prior to myelination (day 6), oligodendrocytes of the corpus callosum have reticular networks of CNP-containing filopodia, in addition to abundant CNP throughout the cytoplasm. Some glioblast-like cells of the subventricular zone are also immunoreactive to anti-CNP, suggesting that, as progenitors of oligodendroglia, they express this myelination-related protein as one of the earliest events in myelinogenesis. Following the commencement of myelination (day 15), many oligodendrocytes lose much of their lacelike network of fine projections, possessing, instead, larger CNP-filled processes that extend to myelin-bearing fibers. CNP was always found only in the cytoplasm-containing compartments of the cells and myelin sheaths; neither lamellae nor cellular membranes were immunostained. These data support our contention that CNP is not an intrinsic membrane protein, despite its strong interaction with membrane components when cells are disrupted. In mutant (mld) mice (day 25), the many distended and uncompacted oligodendroglial processes that invest axons with only a few turns of membrane contained cytoplasmic CNP, accounting for the elevated levels of CNP activity previously noted in tissue fractions.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1987

Immunological evidence for the presence of myelin-related integral proteins in the CNS of hagfish and lamprey.

Antibodies against myelin proteins were utilized in the analysis of total particulate material from the brains of the agnathan hagfish and lamprey. Immunoblotting revealed in both species the presence of bands at 50,000 dalton that reacted with anti-bovine PNS-P0 antibodies. Single bands of 34,000 dalton and 51,000 dalton were immunodetected with anti-trout CNS-36K antibodies in lamprey and hagfish, respectively. Antibodies against mammalian myelin basic protein (MBP) and proteolipid protein (PLP) were not recognized. In spite of the lack of multilayered myelin in agnatha, the presence of myelin-related integral proteins suggests that agnathan glial cells have already acquired the capacity to synthesize some proteins that are similar to typical myelin proteins. This represents a crucial evolutionary step towards myelination.

Animals↗
PubMed1987

Expression of only one myelin basic protein allele in mouse is compatible with normal myelination.

Myelin deficiency (mld) is an autosomal recessive mutation in mice characterized by a severe myelin deficit in the central nervous system (CNS). The primary defect in mld is a reduction of the synthesis of the myelin basic protein (MBP) and probably lies in a regulatory element of the MBP gene. In young mld heterozygotes, the MBP mRNA and MBP levels are intermediate. In order to study whether reduced levels of MBP gene expression affect myelination, we determined the levels of MBP mRNA and MBP itself in mld heterozygous and control brains, at different ages during development. Total proteins and MBP were also measured in myelin isolated at 25 and 85 days of age. Myelin proteins were analyzed by SDS-PAGE. In addition, we carried out a morphometric analysis on 25- and 85-day-old optic nerves. Our results indicate that in spite of a roughly 50% reduction of MBP gene expression (compared to controls), the amounts of myelin isolated and the concentration of MBP in myelin were normal in heterozygous brains. Nevertheless, morphometric analyses of optic nerves, which myelinate later than the brainstem, showed thinner myelin sheaths in 25-day-old heterozygotes when compared to controls. This difference disappeared at 85 days of age. These results indicate that normal mice synthesize MBP in excess. The synthesis of this extramyelinic pool of MBP represents a safety factor allowing normal myelination to proceed even when MBP synthesis is severely reduced. In mld heterozygotes, a 30-50% reduction of this rate of synthesis can represent a limiting factor and locally delay myelin deposition without affecting the overall myelin content or myelin composition in heterozygous adult brains.

Aging↗
PubMed1987

A glycosylated proteolipid protein is common to CNS myelin of recent lungfish (Ceratodidae, Lepidosirenidae).

1. Myelin proteins from the CNS of recent lungfish (Lepidosiren paradoxa, Protopterus dolloi, Neoceratodus forsteri) were separated and analysed by staining and immunoblotting. 2. All species showed a glycosylated component (g-PLP) that cross-reacted with antibodies against tetrapod proteolipid protein (PLP), indicating phylogenetic relationships with amphibia. 3. Actinopterygian IP or teleostean 36k components were not detectable in lungfish CNS myelin. 4. The identical size of g-PLPs from Lepidosiren and Protopterus (Mr = 29,000) underlines the close relationship of the Lepidosirenidae. The smaller size of g-PLP from the ceratodidan Neoceratodus forsteri (Mr = 27,500) pointed to an earlier diversion.

Animals↗
PubMed1987

Three ATPase activities have an abnormal developmental time course in trembler sciatic nerves.

Trembler mutant mice are affected by a peripheral neuropathy characterized by hypomyelination, demyelination, and Schwann cell proliferation. In adult mutants, supernumerary Schwann cells form membranous structures known as 'onion-bulb' formations. The activities of the Na+, K+-ATPase and of two ouabain-insensitive Mg2+-ATPases were investigated in sciatic nerves of young and adult mutants. The Na+, K+-ATPase activities were 92 and 76% of the control values in young and adult mutants, respectively. By immunoblot analysis, the alpha-subunit of the Na+, K+-ATPase had an identical apparent molecular weight in controls at both ages and in young mutants. In adult mutants, on the contrary, the alpha-subunit appeared smaller by about 2 kd, similar to that in kidney, indicating that the Na+, K+-ATPase was localized mainly on supernumerary Schwann cells. In addition, in the mutants, the developmental increase of both the mitochondrial and the nonmitochondrial Mg2+-ATPase was abnormally high. We suggest that the abnormal increase of the nonmitochondrial Mg2+-ATPase activity during development reflects an enrichment of that enzyme in 'onion-bulb' formations.

Animals↗
PubMed1986

Trembler mouse Schwann cells in culture: anomalies in the synthesis of lipids and proteins.

We investigated the biochemical and growth properties of Schwann cells from the sciatic nerve of Trembler and unaffected mice in culture. Both Trembler and control cultures showed similar growth rates. The specific activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and enzymes involved in lipid metabolism of cerebrosides and sulfatides were studied. UDP-galactose: ceramide galactosyltransferase was significantly decreased in Trembler cultures less than 21 days in vitro. No differences were found in the specific activities of cerebroside sulfotransferase, arylsulfatase A or CNP between Trembler and control cultures. Schwann cells from Trembler and control mice were labeled with [35S]methionine and the protein analyzed by two-dimensional gel electrophoresis. Our study revealed few but consistent differences in the protein pattern synthesized by the Trembler Schwann cells.

Animals↗
PubMed1986

Expression of myelin proteins characteristic of fish and tetrapods by Polypterus revitalizes long discredited phylogenetic links.

CNS myelin constituents were used as evolutionary markers to study the controversial relationships of Polypterus with bony fishes, lungfishes and amphibians. The occurrence in Polypterus CNS of myelin proteins similar to those observed in the sterlet confirms its close relationship to Chondrostei. However, the simultaneous presence of proteolipid protein (PLP) demonstrates the existence of a long discredited relationship between Polypterus and tetrapods, and also with the lungfish Protopterus, an ally of tetrapods. As in the lungfish Protopterus, Polypterus cerebrosides and sulfatides contained alpha-hydroxy fatty acids. In contrast to Protopterus CNS myelin which carries glycosylated PLP but lacks Po-like component and the 36 kDa protein, Polypterus possesses these two bony fish myelin components. Furthermore, the presence of aglycosylated PLP in Polypterus, as in higher vertebrates, differentiates it from Protopterus. The simultaneous presence in Polypterus of myelin constituents from fish and land vertebrates indicates that Polypterids occupy an unusual intermediate phylogenetic position. The near absence of 2',3'-cyclic nucleotide 3'-phosphodiesterase activity in Polypterus. Protopterus, and in other fishes, confirmed by the lack of Wolfgram protein, establishes this myelin enzyme as the only CNS myelin constituent specifically expressed by tetrapods.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1986

Myelin lipids: a phylogenetic study.

The lipid composition of CNS and PNS myelin was studied in rat, Xenopus, trout and Torpedo. The main difference lay in the proportion of cerebrosides, which decreased in the sequence rat greater than Xenopus greater than Torpedo greater than trout. In addition Torpedo CNS and PNS myelins were extremely rich in sulfatides. In some respects, Torpedo appeared closer to tetrapods than trout. Otherwise the proportion of the different lipid classes did not reveal any clear evolutionary trends. The presence of hydroxylated galactolipids in CNS myelin was investigated in several additional species. Considerable amounts were found in Torpedo, Polypterus, Protopterus, lizard, and chicken, with the highest values in rat and anurans. Only very small amounts of hydroxylated cerebrosides were detected in trout and in axolotl, while newt had none. This parameter appears therefore of doubtful usefulness for phylogenetic studies. In contrast to myelin proteins, myelin lipids are of limited value for establishing phylogenetic relationships among vertebrates.

Amphibians↗
PubMed1986

Absence of myelin basic protein in an improved purified duck embryo rabies vaccine.

The encephalitogenic potential of rabies vaccines prepared from nervous tissue is a result of the presence of myelin basic protein. Vaccines prepared from duck embryos are economical and efficient, but, occasionally, cases of allergic encephalomyelitis have been reported. An improved rabies vaccine has been developed that contains the classical Pitman Moore strain of rabies virus grown in embryonated duck eggs. This vaccine has been highly purified and enriched in immunologically effective rabies virus glycoprotein antigen. We have searched for the presence of myelin basic protein using sensitive radioimmunological and immunoblotting techniques. Whereas the classical duck embryo rabies vaccine contained small amounts of myelin basic protein, in the improved purified duck embryo rabies vaccine, none could be detected.

Animals↗
PubMed1986

Mice heterozygous for the mld mutation have intermediate levels of myelin basic protein mRNA and its translation products.

Myelin-deficiency (mld) is an autosomal recessive mutation in mice exhibiting a severe deficit in the synthesis of myelin basic protein (MBP). In order to understand the mechanisms involved in the regulation of MBP synthesis in the mld mutation, we examined the amount of MBP and MBP-specific mRNA in control, heterozygous and homozygous mld brains. In vitro translation of poly(A)+ RNA in a cell-free system, in situ hybridization, and filter hybridization with a radiolabelled probe pMBP-1 after dot or Northern blotting were used in this study. The levels of MBP and MBP-specific mRNA were very low but detectable in mld homozygotes, and intermediate in heterozygotes. MBP specific mRNA from mutants, and its translation products, were of normal size. These results show that the mld mutation is expressed co-dominantly in heterozygotes and affects a cis-acting regulatory element controlling the MBP gene.

Animals↗
PubMed1986

Central nervous system myelin of teleosts: comparative electrophoretic analysis of its proteins by staining and immunoblotting.

CNS myelin was isolated from 24 teleostean fishes and the proteins were analyzed by staining and immunoblotting. All species showed a 36 K protein, two or more glycosylated hydrophobic intermediate protein (IP) components and several myelin basic protein bands (BP). The 36 K protein was specific for teleostean fishes. The IP and BP components displayed substantial variations in their proportions as well as in molecular sizes when comparing the different teleosts. This contrasts with CNS myelin proteins which appear more stable in terrestrial vertebrates.

Animals↗
PubMed1986

Myelin instability and oligodendrocyte metabolism in myelin-deficient mutant mice.

During the active phase of myelination in myelin-deficient mutant mice (mld), myelin basic protein (MBP) synthesis is defective and the myelin lamellae are uncompacted. In these mutants, we found a fast metabolism of the myelin-associated glycoprotein (MAG) and of sulfatides, and the presence of cholesterol esters and a degradation product of MAG, dMAG, indicating that mld myelin was unstable. The increased synthesis of MAG and Wolfgram protein, two proteins present in uncompacted myelin sheath and paranodal loops, was demonstrated by high levels of messengers. Simultaneously, we found an accumulation of inclusion bodies, vacuoles, and rough endoplasmic reticulum in mld oligodendrocytes. This material was heavily immunostained for MAG. Furthermore, the developmental change between the two molecular forms of MAG (p72MAG/p67MAG) was delayed in mld mice. In 85-d-old mld mice, the MBP content increased and myelin lamellae became better compacted. In these mutants, dMAG was absent and MAG mRNAs were found in normal amounts. Furthermore, the fine structure of mld oligodendrocytes was normal and the MAG immunostaining was similar to age-matched controls. These results support a functional role for MBP in maintaining the metabolic stability and the compact structure of myelin. Furthermore, in the absence of MBP and myelin compaction, the regulation of the synthesis of at least two membrane proteins related to myelin cannot proceed.

Age Factors↗
PubMed1986

Major central nervous system myelin glycoprotein of the African lungfish (Protopterus dolloi) cross-reacts with myelin proteolipid protein antibodies, indicating a close phylogenetic relationship with amphibians.

CNS myelin was isolated from the spinal cord of the African lungfish Protopterus dolloi. Its proteins consisted of (1) two basic proteins (16,000 and 18,500 apparent Mr) that reacted with anti-human CNS myelin basic protein antibodies and (2) a major protein (29,000 apparent Mr) that stained with concanavalin A-horseradish peroxidase and bound to anti-rat CNS myelin proteolipid protein (PLP) antibodies. This dominant 29,000 Mr protein showed no reaction with antibodies against the major bovine PNS myelin glycoprotein P0. Following treatment with endoglycosidase F the 29,000 Mr protein was reduced in size to a 26,000 apparent Mr component that no longer bound concanavalin A but retained the anti-PLP reactivity. These results agree with a concanavalin A-binding oligosaccharide linked through asparagine to a protein backbone of PLP homology. The major 29,000 Mr lungfish CNS myelin protein was therefore termed g-PLP (glycosylated proteolipid protein). This is the first report demonstrating the occurrence of a PLP-cross-reactive protein in CNS myelin of a fish. It attests to the close phylogenetic relationship of lungfishes to amphibians. Amphibians were previously recognized as the oldest class bearing PLP in its CNS myelin.

Amphibians↗
PubMed1986

Dexamethasone stimulates the biochemical differentiation of fetal forebrain cells in reaggregating cultures.

The influence of dexamethasone on the development of neurons and oligodendrocytes was studied in serum-free, aggregating rat brain cell cultures. Synaptogenesis and myelination occur in this culture system. The concentration of myelin basic protein and the activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase were used as oligodendroglia and myelin markers. Choline acetyltransferase and acetylcholinesterase served as neuronal markers, glutamine synthetase reflected astrocyte differentiation, while ornithine decarboxylase served as a general marker for cell growth and maturation. This study showed that dexamethasone stimulated the differentiation of cholinergic neurons and astrocytes. The effect of dexamethasone on oligodendroglial differentiation and myelination depended on the stage of development: during the early phase of myelination dexamethasone had a stimulatory effect, whereas at a later stage it showed a significant inhibition.

Acetylcholinesterase↗