Crucial role for the myelin-associated glycoprotein in the maintenance of axon-myelin integrity.
It has recently been shown that mice deficient in the gene for myelin-associated glycoprotein develop normal myelin sheaths in the peripheral nervous system. Here we report that in mutant mice older than 8 months the maintenance of axon-myelin units is disturbed, resulting in both axon and myelin degeneration. Morphological features include those typically seen in human peripheral neuropathies, where demyelination-induced Schwann cell proliferation and remyelination lead to the formation of so-called onion bulbs. Expression of tenascin-C, a molecule indicative of peripheral nerve degeneration, was up-regulated by axon-deprived Schwann cells and regenerating axons were occasionally seen. Myelin-associated glycoprotein thus appears to play a crucial role in the long-term maintenance of the integrity of both myelin and axons.
Fruttiger
M
M
Department of Neurobiology, Swiss Federal Institute of Technology, Hönggerberg, Zurich.
Montag
D
D
Schachner
M
M
Martini
R
R
D000818:Animals; D001369:Axons / Q000502:physiology*; D001917:Brachial Plexus / Q000378:metabolism / Q000648:ultrastructure; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005267:Femoral Nerve / Q000378:metabolism / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009185:Myelin Proteins / Q000502:physiology*; D009186:Myelin Sheath / Q000502:physiology*; D018992:Myelin-Associated Glycoprotein; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012584:Sciatic Nerve / Q000378:metabolism / Q000648:ultrastructure; D019063:Tenascin
D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; D009419:Nerve Tissue Proteins; D019063:Tenascin