Myelin-associated glycoprotein is a myelin signal that modulates the caliber of myelinated axons

Xinghua Yin, Thomas O. Crawford, John W. Griffin, Pang Hsien Tu, Virginia M.Y. Lee, Chumei Li, John Roder, Bruce D. Trapp

Research output: Contribution to journalArticle


Myelination increases neuronal conduction velocity through its insulating properties and an unidentified extrinsic effect that increases axonal caliber. Although it is well established that demyelination can cause axonal atrophy, the myelin molecule that regulates axonal caliber is not known. Loss of the structural proteins of compact peripheral nervous system (PNS) myelin, P(o) protein, and myelin basic protein does not lead to axonal atrophy. This study demonstrates that mice with a null mutation of the myelin-associated glycoprotein (MAG) gene have a chronic atrophy of myelinated PNS axons that results in paranodal myelin tomaculi and axonal degeneration. Absence of MAG was correlated with reduced axonal calibers, decreased neurofilament spacing, and reduced neurofilament phosphorylation. Because axonal atrophy and degeneration in MAG-deficient mice occur in the absence of inflammation, hypomyelination, significant demyelination- remyelination, or gain of function mutations, these data support a functional role for MAG in modulating the maturation and viability of myelinated axons.

Original languageEnglish (US)
Pages (from-to)1953-1962
Number of pages10
JournalJournal of Neuroscience
Issue number6
StatePublished - Mar 15 1998


  • Axonal atrophy
  • Axonal caliber
  • Myelin-associated glycoprotein
  • Neurofilament phosphorylation
  • Neurofilament spacing
  • Paranodal tomaculi

ASJC Scopus subject areas

  • Neuroscience(all)

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