Mice deficient for the myelin-associated glycoprotein show subtle abnormalities in myelin.
Using homologous recombination in embryonic stem cells, we have generated mice with a null mutation in the gene encoding the myelin-associated glycoprotein (MAG), a recognition molecule implicated in myelin formation. MAG-deficient mice appeared normal in motor coordination and spatial learning tasks. Normal myelin structure and nerve conduction in the PNS, with N-CAM overexpression at sites normally expressing MAG, suggested compensatory mechanisms. In the CNS, the onset of myelination was delayed, and subtle morphological abnormalities were detected in that the content of oligodendrocyte cytoplasm at the inner aspect of most myelin sheaths was reduced and that some axons were surrounded by two or more myelin sheaths. These observations suggest that MAG participates in the formation of the periaxonal cytoplasmic collar of oligodendrocytes and in the recognition between oligodendrocyte processes and axons.
Montag
D
D
Department of Neurobiology, Swiss Federal Institute of Technology Hönggerberg, Zürich, Switzerland.
Giese
K P
KP
Bartsch
U
U
Martini
R
R
Lang
Y
Y
Blüthmann
H
H
Karthigasan
J
J
Kirschner
D A
DA
Wintergerst
E S
ES
Nave
K A
KA
D000818:Animals; D001483:Base Sequence; D001522:Behavior, Animal; D001921:Brain / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis / Q000235:genetics; D004247:DNA / Q000737:chemistry; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D009185:Myelin Proteins / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D009186:Myelin Sheath / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D018992:Myelin-Associated Glycoprotein; D009836:Oligodendroglia / Q000737:chemistry; D009900:Optic Nerve / Q000648:ultrastructure; D010525:Peripheral Nerves / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D015183:Restriction Mapping; D012583:Schwann Cells / Q000737:chemistry
D015816:Cell Adhesion Molecules, Neuronal; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; D012333:RNA, Messenger; D004247:DNA