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Results for “Myelin Basic Protein”

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PubMed1977

Cellular hypersensitivity in attacks of multiple sclerosis. I. A comparative study of migration inhibitory factor production and lymphoblastic transformation in response to myelin basic protein in multiple sclerosis.

Although cell-mediated hypersensitivity to basic myelin protein has been demonstrated in multiple sclerosis with use of cell migration assays, results with the lymphoblastic transformation technique have been inconclusive. However, prospective studies relating results of lymphoblastic transformation to the clinical course of multiple sclerosis have not been reported. In the present study, both lymphoblastic transformation and migration inhibitory factor assays were used, and results related to the temporal course of multiple sclerosis. Results of the present investigation show that cell-mediated hypersensitivity to myelin basic A1 protein is most significant during exacerbations of multiple sclerosis. Responses obtained employing either the lymphoblastic transformation or migration inhibitory factor assay were equally significant. The results support the hypothesis that a factor suppressing deoxyribonucleic acid synthesis is present in multiple sclerosis and is inhibited by the use of steroids.

Cell Migration Inhibition↗

PubMed1978

The use of gel filtration to follow conformational changes in proteins. Conformational flexibility of bovine myelin basic protein.

The hydrodynamic behavior of bovine myelin basic protein was studied by gel filtration through Sephadex G-100 under conditions which included variations in pH from 2 to 12, variations in ionic strength from 0.01 to 1.5 M at pH 2 and from 0.1 to 2 M at pH 7, and variations in guanidinium chloride concentration from 0 to 6 M. A number of well characterized compact globular proteins were subjected to the same conditions for comparison. Compact globular proteins showed major conformational transitions due to acid, alkali, and guanidinium chloride denaturation and, possibly, minor transitions as well. Myelin basic protein behaved like a flexible linear polyelectrolyte, expanding continuously between pH 11 and pH 2 to 3 at ionic strength 0.1 M and contracting continuously with increase in ionic strength at pH 2 and at pH 7 to the point of salting-out. Relatively low concentrations of guanidinium chloride (approximately 0.5 M) were sufficient to cause the basic protein to expand. With increasing concentration of the denaturant the molecule continued to expand, but in a noncooperative manner. These results demonstrated the lack of significant intramolecular stabilization in the protein.

Animals↗

PubMed2001

Effect of cyclic AMP on the expression of myelin basic protein species and myelin proteolipid protein in committed oligodendrocytes: differential involvement of the transcription factor CREB.

Our previous results support the idea that CREB (cyclic AMP-response element binding protein) may be a mediator of neuroligand and growth factor signals that, coupled to different signal transduction pathways, play different roles at specific stages of oligodendrocyte development. In the early stages, when cells are immature precursors, CREB may play a role as a mediator of protein kinase C (PKC)/mitogen-activated protein kinase (MAPK) pathways regulating cell proliferation. In contrast, at a later stage, when cells are already committed oligodendrocytes, CREB seems to play an important role as a mediator in the stimulation of myelin basic protein (MBP) expression by cyclic AMP (cAMP). In this study, we have investigated whether cAMP and CREB play a role in regulating the expression of all or on the other hand particular MBP isoforms. The results indicated that treatment of committed oligodendrocytes with the cAMP analogue db-cAMP results in a pattern of expression of MBP-related polypeptides that most closely resembles the pattern of MBPs observed in cerebra from adult animals. Experiments in which CREB expression was inhibited using a CREB antisense oligonucleotide, suggested that CREB is involved in the cAMP-dependent stimulation of all the MBP isoforms. In contrast, we have found that db-cAMP stimulates the expression of myelin proteolipid protein (PLP) in a process that occurs despite inhibition of CREB expression. These results support the idea that cAMP stimulates the maturation of oligodendrocytes and stress the fact multiple mechanisms may convey the action of this second messenger modulating oligodendrocyte differentiation and myelination.

Animals↗

PubMed1979

Myelin basic protein treatment of experimental allergic encephalomyelitis in monkeys.

Treatment of experimental allergic encephalomyelitis (EAE) in two strains of monkeys with large amounts of myelin basic basic protein (BP) fails unless an adjunct is also used. In both strains the adjunct by itself is more effective than BP by itself, but in the one strain which could be investigated sufficiently, the combination can be made almost totally effective in reversing EAE. The adjunct varies with the strain of monkey, an antibiotic in Macaca mulatta and a steroid in Macaca fascicularis. Similar adjunctive treatments should be considered in the management of multiple sclerosis, for EAE remains one of the best studied models.

Amino Acids↗

PubMed1982

The relationship of myelin basic protein (arginine) methyltransferase to myelination in mouse spinal cord.

The relationship between the activity of myelin basic protein (arginine) methyltransferase and myelination in the mouse spinal cord has been examined. The activity of this methylase increases between 8 and 45 days postnatal age and correlates well with other parameters of myelination. A comparison of myelin basic protein methylase with histone methylase activity during development indicates that each is a distinct, specific enzyme activity. Together, these results are considered to establish myelin based protein methylase as a myelination-related enzyme.

Aging↗

PubMed1978

In vivo incorporation of 32P into myelin basic protein from normal and quaking mice.

Myelin basic protein in normal mice is phosphorylated. Since phosphorylation can decrease the net positive charge of the myelin basic protein, this could affect molecular interactions between this protein and other myelin components. In this study 32P incorporation into small and large components of the myelin basic protein was studied in immature and young adult mice and also in Quaking mutants which have a severe myelin deficit. We found a short half-life of 32P in myelin basic protein. The 32P specific activity of myelin basic protein was higher in immature and Quaking mice than in young adult animals. Of the 32P-labeled basic proteins of control and Quaking mice, the small component had a slightly higher specific activity than the large component. Although the small basic protein is quantitatively decreased in Quaking mice, the ratio of specific activity of small to large basic protein is similar in control and Quaking animals. Since Quaking and immature mice have many uncompacted myelin lamellae, these preliminary results suggest that phosphorylation and dephosphorylation could be involved in compaction mechanisms.

Aging↗

PubMed1984

Anticonvulsive treatment of myelin-deficient (mld) mice improves survival and confirms the delayed increase of myelin basic protein.

Myelin-deficient (mld) mutant mice were treated with phenobarbital between 60 and 90 d of age. The survival rate at 90 d increased from 1.4% in untreated mutants to 46% in those who received phenobarbital. This is evidence that apneic spells during tonic seizures are a major cause of death in mld mice. Myelin basic protein (MBP) content of brain homogenates from treated mld mice increased significantly between 30 and 90 d. MBP was present in myelin purified from the 90-d-old treated mld mice. These results demonstrate that the MBP increase, which occurs after the active phase of myelin formation is completed, is a general phenomenon and is not caused by the selection of a small and mildly affected subpopulation of mutants.

Animals↗

PubMed1989

Interaction and fusion of unilamellar vesicles containing cerebrosides and sulfatides induced by myelin basic protein.

The effects of myelin basic protein on the aggregation, lipid bilayer merging, intercommunication of aqueous compartments and leakage of small unilamellar vesicles of egg phosphatidylcholine containing different proportions of galactocerebroside and sulfatide were investigated. This was performed employing light scattering, absorbance changes and fluorescence assays (resonance energy transfer, Terbium/dipicolinic acid assay and carboxyfluorescein release). The apposition of membranes rapidly induced by myelin basic protein is enhanced by sulfatide but reduced by galactocerebroside compared to vesicles of egg phosphatidylcholine alone. On the other hand, the presence of either glycosphingolipid in the membrane interferes with the induction by myelin basic protein of lipid bilayer merging, subsequent fusion and changes of the membrane permeability. Our results support an important modulation by sulfatide and galactocerebroside on the interactions among membranes induced by myelin basic protein, depending on the relative proportions of the glycosphingolipids and phosphatidylcholine.

Cerebrosides↗

PubMed1986

Covalent linkage of phospholipid to myelin basic protein: identification of serine-54 as the site of attachment.

The peptide portion of the lipopeptide isolated from bovine myelin basic protein contained glycine, lysine, and serine in a 2:1:1 molar ratio as determined by amino acid analysis. The N-terminus of the peptide was determined to be glycine. The tetrapeptide Gly53-Ser-Gly-Lys56 was the only segment of myelin basic protein that matched the above two characteristics. This tetrapeptide is highly conserved among the myelin basic proteins sequenced so far. After the selective degradation of the lipopeptide, phosphoserine was identified in the acid hydrolysate, thus indicating that Ser-54 of myelin basic protein in bovine brain is the site of attachment of polyphosphoinositide. Interestingly, serine-54 of myelin basic protein can be phosphorylated by the endogenous protein kinase myelin. However, myelin basic protein phosphorylated by the catalytic subunit of an exogenous soluble protein kinase failed to produce radioactively labeled lipopeptide. Hence the endogenous enzymes of myelin are thought to be involved in the formation of the covalent linkage between polyphosphoinositide and myelin basic protein. The conservation in sequence suggests a possible important structural role for the "phospholipidation" of myelin basic protein.

Amino Acids↗

PubMed1992

Susceptibility of myelin proteins to a neutral endoproteinase: the degradation of myelin basic protein (MBP) and P2 protein by purified bovine brain multicatalytic proteinase complex (MPC).

Multicatalytic proteinase complex (MPC) was isolated from bovine brain and the susceptibility of myelin basic protein (MBP) and P2 protein of bovine central and peripheral nervous system was examined. SDS-polyacrylamide electrophoretic analysis of purified MPC revealed protein bands of molecular weight ranging from 22-35 kDa. The enzyme is activated by SDS at a concentration less than 0.01%. Upon incubation with MPC, purified MBP and P2 proteins were degraded into smaller fragments. There was a 57% and 100% loss of MBP at 2 and 6 hours of incubation. The P2 protein which is not susceptible to any endogenous non-lysosomal enzyme thus far studied was digested into small peptide fragments only in the presence of SDS (0.01%) and not in its absence. These results indicate that MPC which is active at physiological conditions may have a role in the turnover of myelin proteins and in demyelinating diseases.

Amino Acid Sequence↗

PubMed1975

Cellular immunity to human basic myelin protein in women with dysplasia and carcinoma in situ of the cervix.

Sensitization to human myelin basic protein or encephalitogenic factor (EF), and antigen thought to be analogous to different human tumours, can be measured by the macrophage migration inhibition test (MMI). The MMI test was done on one occasion in 51 women with dysplasia and carcinoma in situ of the cervix; 20 women with non-malignant gynaecological conditions served as controls. Sensitization to EF was found in 71 per cent of women with carcinoma in situ and 42 per cent of women with dysplasia. None of the controls showed sensitization. Sensitization could not be related to histological evidence for cellular infiltration within the cervix.

Adult↗

PubMed1976

Blocking the encephalitogenic activity of the C-terminal part of the basic myelin protein in rabbits by treatment with serum.

Peptides HNB-92-169 and 116-169, tyr, derivatives of the C-terminal part of bovine myelin basic protein, sensitize rabbits for experimental allergic encephalomyelitis (EAE). Dissolving these peptides in heat-inactivated normal guinea-pig, human, or monkey serum immediately before emulsification with Freund's complete adjuvant (FCA) abrogated their disease-inducing activity. Dissolving them in homologous or autologous serum only slightly affected the encephalitogenicity.

Animals↗

PubMed1981

Developmental regulation of myelin basic protein in dispersed cultures.

The expression of myelin basic protein, a major component of the myelin membrane, was studied in the absence of myelin formation in a unique situation in which these two processes have been uncoupled. The oligodendrocytes that contained myelin basic protein were identified by immunofluorescence in primary dispersed cultures derived from 20-day-old fetal rat brain. Their number increased 20-fold between 15 and 34 days in culture. Morphologically identifiable myelin was never observed. The oligodendrocytes elaborated a complex network of processes and membranous sheets resembling "unfurled" myelin. Myelin basic protein appeared concomitantly in the perikaryon, processes, and membranous sheets of the oligodendrocytes and remained distributed in these compartments throughout the culture period. The oligodendrocytes synthesized the four forms of myelin basic protein found in rodent brain with molecular weights of 21,500, 18,500, 17,000, and 14,000 and modulated their expression with time in culture. The onset of rapid myelin basic protein accumulation, as measured by radioimmunoassay, took place after 25 days in culture. Myelin basic protein accumulated at the rate of 0.2 fmol per oligodendrocyte per day and reached a level of 300 pmol/mg of protein by 34 days. By 60 days, the amount of myelin basic protein had declined to 100 pmol/mg of protein, a level maintained up until at least 120 days. When the amount of myelin basic protein was correlated with the number of oligodendrocytes, it was estimated that each induced cell contained on average 1 fmol of this protein at the three time points (15, 28, and 34 days in culture) at which cells were counted. Our results indicate that the accumulation, modulation of the molecular forms, and insertion of myelin basic protein into the membrane can occur in the absence of myelin formation, but that continued metabolic stability, subcellular sequestration, and fine control of the relative proportions of the different forms of myelin basic protein may be dependent on myelin morphogenesis.

Animals↗

PubMed1988

Recombination within the upstream gene of duplicated myelin basic protein genes of myelin deficient shimld mouse results in the production of antisense RNA.

The myelin deficient shimld mouse is an autosomal recessive mutant, characterized by hypomyelination in the central nervous system. The expression of the myelin basic protein (MBP) gene is inhibited transcriptionally. The MBP gene is duplicated tandemly in mld, and exons 3 to 7 of the upstream copy is inverted. In the present studies, we determined the approximate position of the 5' boundary and the nucleotide sequence surrounding the 3' boundary of the inversion and found a number of sequences homologous to the switching regions of mouse immunoglobulin heavy chain gene and J regions of human T cell receptor genes. Antisense RNA complementary to exons 3 and 7, which correspond to the inverted segment, was detected by RNase protection studies. This abnormal transcript was also shown to elongate through the inverted segment to reach the transcription initiation site of the downstream gene.

Animals↗

PubMed1978

Myelin basic protein demonstrated immunocytochemically in oligodendroglia prior to myelin sheath formation.

A specific antibody to myelin basic protein has been used to localize the protein in developing rat oligodendroglia and myelin. Basic protein is found in the oligodendroglial cytoplasm of anterior commissures of 5- and 7-day old rats before the beginning of myelination. Staining of basic protein in oligodendroglia increases, becoming most intense during early myelination; it decreases during rapid myelination. Staining intensity of oligodendroglia is dependent upon age, brain region, and nervous tract studied. In myelin, reaction of basic protein with antibody decreases when large compact sheaths are present, unless tissue sections are first treated with alcohol.

Animals↗

PubMed1986

Oligodendrocyte adhesion activates protein kinase C-mediated phosphorylation of myelin basic protein.

When isolated adult oligodendrocytes adhere to a substratum myelinogenesis occurs. Investigation of the mechanism by which this happens indicated that the oligodendrocyte-substratum interaction activated protein kinase C-dependent phosphorylation of myelin basic protein and promoted the synthesis of myelin basic protein. In addition, when agents that activate protein kinase C (second messenger diacylglycerol or a tumor-promoting phorbol ester) were added to nonattached oligodendrocytes, they mimicked the influence of the substratum by inducing phosphorylation of myelin basic protein; and reagents that increase cellular adenosine 3', 5'-monophosphate (cyclic AMP) inhibited phosphorylation of myelin basic protein. Thus, at least in vitro, the interaction between oligodendrocytes and the substratum may mediate myelinogenic events, and phosphorylation of myelin basic protein may be an early requirement in the sequence of steps that ultimately results in myelin formation.

1-Methyl-3-isobutylxanthine↗

PubMed2004

Generation of transgenic mice expressing insulin-like growth factor-1 under the control of the myelin basic protein promoter: increased myelination and potential for studies on the effects of increased IGF-1 on experimentally and genetically induced demyelination.

In order to investigate a role for insulin-like growth factor-1 (IGF-1) in ameliorating the effects of demyelinating events and potentiating remyelination, we have generated transgenic (tg) mice expressing IGF-1 under the control of the myelin basic protein promoter. Heterozygous tg mice expressed the highest levels of IGF-1 in brain during the most active periods of myelination as determined by Western and Northern blotting. A high level of expression was found throughout the lives of the tg mice. There was no increased expression of IGF-1 in other organs. The brains of heterozygous mice were larger than those of normal mice by 2 weeks of age, and they continued to increase in size for several months. Light and electron microscopy showed extensive myelination of axons. Behavioral studies of the older heterozygous mice documented difficulty with balance. This new tg mouse model can be bred to mice that are heterozygous for genetic leukodystrophies to produce eventually mice that are affected with a given leukodystrophy but overexpress IGF-1 during myelination and remyelination. It will be interesting to see if overexpression of IGF-1 can modulate the pathological and clinical features of the inherited leukodystrophies with or without supplemental therapies.

Animals↗

PubMed1987

Myelin basic protein and demyelinating diseases.

Myelin basic protein (MBP) is a major protein component of myelin sheath. Primarily because of its ability to induce experimental allergic encephalomyelitis (EAE) in animals, this protein has been considered to play an important role in the pathogenesis of multiple sclerosis (MS), which is one of the most common demyelinating diseases. Its precise measurement in the cerebrospinal fluid (CSF) has been uncommonly difficult, mainly due to immunoheterogeneity of MBP or MBP-like material. More recently, highly sensitive radioimmunoassay techniques utilizing well-characterized antisera have been developed that facilitated its use in the management of MS. The clinical course of MS is highly variable, and the disease is characterized by periods of remission and relapses. Many studies have demonstrated the release of MBP during relapses and elevated levels of MBP in the CSF can be detected if lumbar puncture is performed within 7 days of the onset of neurologic symptoms suggestive of MS. However, the presence of MBP is not an absolute indicator of MS, as elevated MBP levels are also frequently observed in other demyelinating diseases.

Antigen-Antibody Complex↗