Unraveling the differential expression of the two isoforms of myelin-associated glycoprotein in a mouse expressing GFP-tagged S-MAG specifically regulated and targeted into the different myelin compartments

• Published in: Molecular and cellular neuroscience 2006-04, Vol.31 (4), p.613-627
• Main Authors: Erb, Michael, Flueck, Bettina, Kern, Frances, Erne, Beat, Steck, Andreas J., Schaeren-Wiemers, Nicole
• Format: Article
• Language: English
• Subjects: Animals; Axon-glia interaction; Axons - metabolism; Axons - ultrastructure; Brain - cytology; Brain - metabolism; Gene Expression Regulation, Developmental; GFP-transmembrane fusion protein; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Mice; Mice, Inbred C57BL; Mice, Transgenic; Models, Biological; Myelin Sheath - metabolism; Myelin Sheath - ultrastructure; Myelin-associated glycoprotein; Myelin-Associated Glycoprotein - genetics; Myelin-Associated Glycoprotein - metabolism; Myelinogenesis; Nervous system; Peripheral Nerves - cytology; Peripheral Nerves - metabolism; Protein Isoforms - genetics; Protein Isoforms - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RNA, Messenger - metabolism; Sciatic Nerve - cytology; Sciatic Nerve - metabolism; Targeting and sorting
• ISSN: 1044-7431; 1095-9327
• DOI: 10.1016/j.mcn.2005.12.001

The two myelin-associated glycoprotein (MAG) isoforms are cell adhesion molecules that differ only in their cytoplasmic domains, but their specific roles are not well understood. In this study, we present a transgenic mouse line that specifically expresses GFP-tagged S-MAG correctly regulated and targeted into the myelin sheath allowing the specific discrimination of L- and S-MAG on the subcellular level. Here, we describe the differential expression pattern and spatial distribution of L- and S-MAG during development as well as in the adult central and peripheral nervous system. In peripheral nerves, where S-MAG is the sole isoform, we observed S-MAG concentrated in different ring-like structures such as periaxonal and abaxonal rings, and discs spanning through the compact myelin sheath perpendicular to the axon. In summary, our data provide new insight in the subcellular distribution of the two isoforms fundamental for the understanding of their specific functions in myelin formation and maintenance.