Abstract
The myelin-associated glycoprotein (MAG) is a member of the immunoglobulin gene superfamily that is selectively expressed by myelin- forming cells. A developmentally regulated, alternative splicing of a single MAG transcript produces two MAG polypeptides (72 and 67 kD) in the central nervous system (CNS). MAG occurs predominantly as the 67-kD polypeptide in the peripheral nervous system (PNS). This study determined the subcellular localization of CNS MAG at different postnatal times when the 72-kD form (7-d) and 67-kD form (adult) are quantitatively abundant. These distributions were also compared to those of MAG in the PNS. In adult rat, MAG is selectively enriched in periaxonal membranes of CNS myelin internodes. This restricted distribution differs from that in PNS myelin internodes where MAG is also enriched in paranodal loops, Schmidt-Lanterman incisures, and mesaxon membranes. In 7-d-old rat CNS, MAG was associated with periaxonal membranes during axonal ensheathment and enriched in Golgi membranes and cytoplasmic organelles having the appearance of multivesicular bodies (MVBs). MAG-enriched MVBs were found in oligodendrocyte perinuclear regions, in processes extending to myelin internodes, and along the myelin internode in outer tongue processes and paranodal loops. MAG-enriched MVBs were not found in oligodendrocytes from adult animals or in myelinating Schwann cells. These findings raise the possibility that the 72-kD MAG polypeptide is associated with receptor-mediated endocytosis of components from the periaxonal space or axolemma during active stages of myelination.
Full Text
The Full Text of this article is available as a PDF (5.4 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arquint M., Roder J., Chia L. S., Down J., Wilkinson D., Bayley H., Braun P., Dunn R. Molecular cloning and primary structure of myelin-associated glycoprotein. Proc Natl Acad Sci U S A. 1987 Jan;84(2):600–604. doi: 10.1073/pnas.84.2.600. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bernier L., Alvarez F., Norgard E. M., Raible D. W., Mentaberry A., Schembri J. G., Sabatini D. D., Colman D. R. Molecular cloning of a 2',3'-cyclic nucleotide 3'-phosphodiesterase: mRNAs with different 5' ends encode the same set of proteins in nervous and lymphoid tissues. J Neurosci. 1987 Sep;7(9):2703–2710. doi: 10.1523/JNEUROSCI.07-09-02703.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown M. S., Anderson R. G., Goldstein J. L. Recycling receptors: the round-trip itinerary of migrant membrane proteins. Cell. 1983 Mar;32(3):663–667. doi: 10.1016/0092-8674(83)90052-1. [DOI] [PubMed] [Google Scholar]
- Colman D. R., Kreibich G., Frey A. B., Sabatini D. D. Synthesis and incorporation of myelin polypeptides into CNS myelin. J Cell Biol. 1982 Nov;95(2 Pt 1):598–608. doi: 10.1083/jcb.95.2.598. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cunningham B. A., Hemperly J. J., Murray B. A., Prediger E. A., Brackenbury R., Edelman G. M. Neural cell adhesion molecule: structure, immunoglobulin-like domains, cell surface modulation, and alternative RNA splicing. Science. 1987 May 15;236(4803):799–806. doi: 10.1126/science.3576199. [DOI] [PubMed] [Google Scholar]
- Frail D. E., Braun P. E. Two developmentally regulated messenger RNAs differing in their coding region may exist for the myelin-associated glycoprotein. J Biol Chem. 1984 Dec 10;259(23):14857–14862. [PubMed] [Google Scholar]
- Frail D. E., Webster H. D., Braun P. E. Developmental expression of the myelin-associated glycoprotein in the peripheral nervous system is different from that in the central nervous system. J Neurochem. 1985 Oct;45(4):1308–1310. doi: 10.1111/j.1471-4159.1985.tb05559.x. [DOI] [PubMed] [Google Scholar]
- Geuze H. J., Slot J. W., Schwartz A. L. Membranes of sorting organelles display lateral heterogeneity in receptor distribution. J Cell Biol. 1987 Jun;104(6):1715–1723. doi: 10.1083/jcb.104.6.1715. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Geuze H. J., Slot J. W., Strous G. J., Lodish H. F., Schwartz A. L. Intracellular site of asialoglycoprotein receptor-ligand uncoupling: double-label immunoelectron microscopy during receptor-mediated endocytosis. Cell. 1983 Jan;32(1):277–287. doi: 10.1016/0092-8674(83)90518-4. [DOI] [PubMed] [Google Scholar]
- Geuze H. J., Stoorvogel W., Strous G. J., Slot J. W., Bleekemolen J. E., Mellman I. Sorting of mannose 6-phosphate receptors and lysosomal membrane proteins in endocytic vesicles. J Cell Biol. 1988 Dec;107(6 Pt 2):2491–2501. doi: 10.1083/jcb.107.6.2491. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lai C., Brow M. A., Nave K. A., Noronha A. B., Quarles R. H., Bloom F. E., Milner R. J., Sutcliffe J. G. Two forms of 1B236/myelin-associated glycoprotein, a cell adhesion molecule for postnatal neural development, are produced by alternative splicing. Proc Natl Acad Sci U S A. 1987 Jun;84(12):4337–4341. doi: 10.1073/pnas.84.12.4337. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Martini R., Schachner M. Immunoelectron microscopic localization of neural cell adhesion molecules (L1, N-CAM, and MAG) and their shared carbohydrate epitope and myelin basic protein in developing sciatic nerve. J Cell Biol. 1986 Dec;103(6 Pt 1):2439–2448. doi: 10.1083/jcb.103.6.2439. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mostov K. E., Friedlander M., Blobel G. The receptor for transepithelial transport of IgA and IgM contains multiple immunoglobulin-like domains. Nature. 1984 Mar 1;308(5954):37–43. doi: 10.1038/308037a0. [DOI] [PubMed] [Google Scholar]
- Noronha A. B., Hammer J. A., Lai C., Kiel M., Milner R. J., Sutcliffe J. G., Quarles R. H. Myelin-associated glycoprotein (MAG) and rat brain-specific 1B236 protein: mapping of epitopes and demonstration of immunological identity. J Mol Neurosci. 1989;1(3):159–170. doi: 10.1007/BF02918902. [DOI] [PubMed] [Google Scholar]
- Poltorak M., Sadoul R., Keilhauer G., Landa C., Fahrig T., Schachner M. Myelin-associated glycoprotein, a member of the L2/HNK-1 family of neural cell adhesion molecules, is involved in neuron-oligodendrocyte and oligodendrocyte-oligodendrocyte interaction. J Cell Biol. 1987 Oct;105(4):1893–1899. doi: 10.1083/jcb.105.4.1893. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Quarles R. H., Everly J. L., Brady R. O. Evidence for the close association of a glycoprotein with myelin in rat brain. J Neurochem. 1973 Nov;21(5):1177–1191. doi: 10.1111/j.1471-4159.1973.tb07573.x. [DOI] [PubMed] [Google Scholar]
- Quarles R. H., Everly J. L., Brady R. O. Myelin-associated glycoprotein: a developmental change. Brain Res. 1973 Aug 30;58(2):506–509. doi: 10.1016/0006-8993(73)90022-x. [DOI] [PubMed] [Google Scholar]
- Quarles R. H., Johnson D., Brady R. O., Sternberger N. H. Preparation and characterization of antisera to the myelin-associated glycoprotein. Neurochem Res. 1981 Oct;6(10):1115–1127. doi: 10.1007/BF00964417. [DOI] [PubMed] [Google Scholar]
- Salzer J. L., Holmes W. P., Colman D. R. The amino acid sequences of the myelin-associated glycoproteins: homology to the immunoglobulin gene superfamily. J Cell Biol. 1987 Apr;104(4):957–965. doi: 10.1083/jcb.104.4.957. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sternberger N. H., Quarles R. H., Itoyama Y., Webster H. D. Myelin-associated glycoprotein demonstrated immunocytochemically in myelin and myelin-forming cells of developing rat. Proc Natl Acad Sci U S A. 1979 Mar;76(3):1510–1514. doi: 10.1073/pnas.76.3.1510. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tokuyasu K. T. Application of cryoultramicrotomy to immunocytochemistry. J Microsc. 1986 Aug;143(Pt 2):139–149. doi: 10.1111/j.1365-2818.1986.tb02772.x. [DOI] [PubMed] [Google Scholar]
- Trapp B. D., Andrews S. B., Wong A., O'Connell M., Griffin J. W. Co-localization of the myelin-associated glycoprotein and the microfilament components, F-actin and spectrin, in Schwann cells of myelinated nerve fibres. J Neurocytol. 1989 Feb;18(1):47–60. doi: 10.1007/BF01188423. [DOI] [PubMed] [Google Scholar]
- Trapp B. D., Bernier L., Andrews S. B., Colman D. R. Cellular and subcellular distribution of 2',3'-cyclic nucleotide 3'-phosphodiesterase and its mRNA in the rat central nervous system. J Neurochem. 1988 Sep;51(3):859–868. doi: 10.1111/j.1471-4159.1988.tb01822.x. [DOI] [PubMed] [Google Scholar]
- Trapp B. D. Distribution of the myelin-associated glycoprotein and P0 protein during myelin compaction in quaking mouse peripheral nerve. J Cell Biol. 1988 Aug;107(2):675–685. doi: 10.1083/jcb.107.2.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Trapp B. D., Quarles R. H. Immunocytochemical localization of the myelin-associated glycoprotein. Fact or artifact? J Neuroimmunol. 1984 Jul;6(4):231–249. doi: 10.1016/0165-5728(84)90011-0. [DOI] [PubMed] [Google Scholar]
- Trapp B. D., Quarles R. H. Presence of the myelin-associated glycoprotein correlates with alterations in the periodicity of peripheral myelin. J Cell Biol. 1982 Mar;92(3):877–882. doi: 10.1083/jcb.92.3.877. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Trapp B. D., Quarles R. H., Suzuki K. Immunocytochemical studies of quaking mice support a role for the myelin-associated glycoprotein in forming and maintaining the periaxonal space and periaxonal cytoplasmic collar of myelinating Schwann cells. J Cell Biol. 1984 Aug;99(2):594–606. doi: 10.1083/jcb.99.2.594. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tropak M. B., Johnson P. W., Dunn R. J., Roder J. C. Differential splicing of MAG transcripts during CNS and PNS development. Brain Res. 1988 Sep;464(2):143–155. doi: 10.1016/0169-328x(88)90006-x. [DOI] [PubMed] [Google Scholar]