In Vitro Synthesis of the Four Mouse Myelin Basic Proteins: Evidence for the Lack of a Metabolic Relationship

Yu, Yi‐Tao; Campagnoni, Anthony T.

doi:10.1111/j.1471-4159.1982.tb07988.x

Cited by 53 publications

(32 citation statements)

References 31 publications

(27 reference statements)

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“…§1734 solely to indicate this fact. In some experiments, mRNA was isolated from a purified polysomal fraction of mouse brain homogenate by using the method previously described (22). This postnuclear polysomal polyadenylylated RNA was used in all the hybridization experiments.…”

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confidence: 99%

“…Unbound RNA was removed by washing the nitrocellulose two times with 2x NaCl/Cit/2x NaCl/Cit = 3 M NaCl/0.3 M Na citrate) at 25°C and four times at 52°C with 0.1 x NaCl/Cit/2 mM EDTA. The hybridized RNA was eluted from the nitrocellulose-bound pNZ111 by boiling for 2 min in 10 mM Tris.HCl/2 mM EDTA, pH 7.4, as described by Patterson and Roberts (32) and translated in a reticulocyte lysate system as described by Yu and Campagnoni (22).…”

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confidence: 99%

“…The origin of the multiplicity of the MBP forms is still obscure. Experiments performed in several laboratories argue against a precursorproduct relationship among the various MBPs (22,40). Two other possible explanations are obvious.…”

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Characterization of mouse myelin basic protein messenger RNAs with a myelin basic protein cDNA clone.

Zeller¹,

Hunkeler²,

Campagnoni³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

116

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Using a family of synthetic tetradecamer oligonucleotides as a primer for cDNA synthesis and a second family of tetradecamers as a hybridization probe, we have prepared and isolated a cDNA clone of mouse myelin basic protein (MBP). The clone, pNZ111, corresponds to the region of the mRNA that codes for an amino acid sequence present in all four major forms of MBP (2)(3)(4)(5). Large amounts of the membrane are produced relative to the size of the myelin-forming cell. The process involves the synthesis of myelin-specific proteins followed by their integration into the growing membrane. During early myelinogenesis, membranes are formed that are loosely whorled around the axon. As myelin maturation proceeds, compaction of these membranes occurs to form the tight multilamellar structure characteristic of myelin.The myelin basic protein (MBP) constitutes about 33% of the protein of the myelin sheath in the central nervous system and 1-10% in the peripheral (6, 7). In most species, the predominant form of the MBP has a molecular mass of 18.5 kilodaltons (kDa), and the primary sequence of this protein is well conserved in animals as distantly related as the chicken, human, and rat (8-10). Two major forms of MBP predominate in rats and mice: one of these corresponds to the single major protein found in other species (18.5 kDa) and the other has a molecular mass of 14 kDa. In rats, the 14-kDa MBP is identical in sequence to the 18.5-kDa MBP, except for an internal deletion of residues 118-158 [numbered according to Martenson (11)] near the carboxyl terminus of the protein (10, 12). Two quantitatively minor forms of MBP have been found in rats and mice-a 21.5-kDa protein that is presumably identical to the 18.5-kDa MBP, except for the inclusion of a 25-30 amino acid sequence in the NH2-terminal half of the molecule and a 17-kDa MBP that bears the same relationship to the 14-kDa MBP (13).Myelination occurs postnatally in mouse brain beginning 8-10 days postpartum and continuing actively for 7-10 wk, with the maximal rate of myelin deposition occurring at about 18 days (4). Maximal synthesis of the 18.5-kDa and 14-kDa MBPs occurs at 18 days in vivo and coincides closely with the peak of myelin synthesis (14). During myelin maturation in the mouse, the proportions of the four MBPs in the membrane change (15-17) and this may be due to alterations in the relative rates of synthesis of the four proteins with age. With maturation, the proportion of the two minor MBPs (i.e., the 21.5 kDa and 17 kDa in myelin falls relative to the 18.5-kDa proteins and the 14-kDa/18.5-kDa MBP ratio increases dramatically. This latter change has been correlated with the relative rate of synthesis of these two proteins in vivo (14). Recently, Carson et al. (18) have identified trace amounts of larger forms of MBP that appear during the early stages of myelination. Identification of these larger forms has depended on immunoreagents and the relationships of the amino acid sequences to the major MBPs have, as yet, not been determined.We have r...

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Characterization of mouse myelin basic protein messenger RNAs with a myelin basic protein cDNA clone.

Zeller¹,

Hunkeler²,

Campagnoni³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

116

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“…Among these proteins, the myelin basic proteins (MBPs),' hydrophobic proteolipid proteins (PLPs), myelin-associated glycoproteins (MAGs), and 2',3'-cyclic nucleotide 3'-phosphorylase (CNP) have been identified (3)(4)(5) and their cDNAs isolated (6)(7)(8)(9). MBPs account for 30-40% of total protein in myelin sheaths and range in size from 14 to 21.5 kD (10,11). These forms are produced from a single primary transcript from a single MBP gene through alternative patterns of RNA splicing (6)(7)(8)(9)(12)(13)(14)(15).…”

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Nuclear proteins in mouse brain cells bind specifically to the myelin basic protein regulatory region.

Lashgari

Devine-Beach²,

Haas³

et al. 1990

J. Clin. Invest.

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Expression of myelin basic protein (MBP) in mice is regulated in a cell-and stage-specific manner during brain development. The MBP control region contains multiple cis-acting elements, shown by in vivo and in vitro assays, which are responsible for its unique pattern of transcription. Using synthetic DNA fragments spanning the MBP control region, we have analyzed nuclear proteins obtained from newborn (2-3 d),. young adult (18-30 d), and adult (60 d) animals; these nuclear proteins form DNA-protein complexes with the MBP regulatory region. Brain extracts from young adult and adult mice showed enhanced binding activities with the sequences supporting transcriptional activation in glial cells.

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“…The four MBPs that are present in rodent myelin have homologous amino acid sequences, including identical amino-and carboxyl-terminal sequences but internal segments of unique amino acid sequence (3). They are translated from four different mRNAs (50), and the four MBP mRNAs can be produced from a single MBP gene by alternative mRNA splicing (12,44). Two PLPs are present in myelin, the major PLP, which has an apparent molecular weight of 25,000, and the closely related proteolipid DM20 (1), which has an apparent molecular weight of 20,000.…”

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Characterization of myelin proteolipid mRNAs in normal and jimpy mice.

Gardinier¹,

Macklin²,

Diniak³

et al. 1986

Mol. Cell. Biol.

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A clone specific for the rat myelin proteolipid protein (PLP) was isolated from a cDNA library made in pUC18 from 17-day-old rat brain stem mRNA. This clone corresponded to the carboxyl-terminal third of the PLP-coding region. The clone was used to identify PLP-specific mRNAs in mouse brain and to establish the time course of PLP mRNA expression during mouse brain development. Three PLP-specific mRNAs were seen, approximately 1,500, 2,400, and 3,200 bases in length, of which the largest was the most abundant. During brain development, the maximal period of PLP mRNA expression was from 14 to 25 days of age, and this was a similar time course to that for myelin basic protein mRNA expression. When the jimpy mouse, an X-linked dysmyelination mutant, was studied for PLP mRNA expression, low levels of PLP mRNA were seen which were approximately 5% of wild-type levels at 20 days of age. When jimpy brain RNA was analyzed by Northern blotting, the PLP-specific mRNA was shown to be 100 to 200 bases shorter than the wild-type PLP-specific mRNA. This size difference was seen in the two major PLP mRNAs, and it did not result from a loss of polyadenylation of these mRNAs.The biosynthesis of the myelin sheath is a crucial part of nervous system development, and as a result, the developmental expression of the myelin protein genes is highly regulated. The normal pattern of myelin protein expression in rodents indicates that little myelin protein expression occurs prenatally or in neonatal animals (2,5,6,8,23,26,28) and that myelin protein synthesis and accumulation increase significantly in the brain at about 10 days after birth, reaching a peak between 15 and 22 days after birth (2,5,6,8,23).Central nervous system myelin contains two major classes of proteins, myelin basic protein (MBP) and proteolipid protein (PLP), which together constitute as much as 80% of the total myelin protein (15,30). The four MBPs that are present in rodent myelin have homologous amino acid sequences, including identical amino-and carboxyl-terminal sequences but internal segments of unique amino acid sequence (3). They are translated from four different mRNAs (50), and the four MBP mRNAs can be produced from a single MBP gene by alternative mRNA splicing (12,44). Two PLPs are present in myelin, the major PLP, which has an apparent molecular weight of 25,000, and the closely related proteolipid DM20 (1), which has an apparent molecular weight of 20,000. PLP and DM20 may have a relationship similar to that found among the four MBPs, since they have identical amino-and carboxyl-terminal sequences (46), and they are very closely related by amino acid composition and by antigenic characteristics. The expression of these myelin proteins correlates closely with the formation of myelin in the developing rat brain, and mouse mutants that are defective in myelin formation show lowered levels of these myelin proteins (4,14,20,25 expression and the genetic deficiency in the shiverer mouse myelination mutant (12,34,44). Several groups have recently isolated cDNA ...

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In Vitro Synthesis of the Four Mouse Myelin Basic Proteins: Evidence for the Lack of a Metabolic Relationship

Cited by 53 publications

References 31 publications

Characterization of mouse myelin basic protein messenger RNAs with a myelin basic protein cDNA clone.

Characterization of mouse myelin basic protein messenger RNAs with a myelin basic protein cDNA clone.

Nuclear proteins in mouse brain cells bind specifically to the myelin basic protein regulatory region.

Characterization of myelin proteolipid mRNAs in normal and jimpy mice.

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