Role of long-range repulsive forces in organizing axonal neurofilament distributions: Evidence from mice deficient in myelin-associated glycoprotein

Sanjay Kumar, Xinghua Yin, Bruce D. Trapp, Michael E. Paulaitis, Jan H. Hoh

Research output: Contribution to journalArticlepeer-review

Abstract

When the axon of a motor neuron is sectioned and visualized by electron microscopy, a two-dimensional distribution of neurofilaments (NFs) with nonrandom spacing is revealed; this ordered arrangement implies the presence of physical interactions between the NFs. To gain insight into the molecular basis of this organization, we characterized NF distributions from mouse sciatic nerve cross sections using two statistical mechanical measures: radial distribution functions and occupancy probability distributions. Our analysis shows that NF organization may be described in terms of effective pairwise interactions. In addition, we show that these statistical mechanical measures can detect differences in NF architecture between wild-type and myelin-associated glycoprotein null mutant mice. These differences are age dependent, with marked contrast between the NF distributions by 9 months of age. Finally, using Monte Carlo simulations, we compare the experimental results with predictions for models in which adjacent NFs interact through rigid cross bridges, deformable cross bridges, and long-range repulsive forces. Among the models tested, a model in which the filaments interact through a long-range repulsive force is most consistent with the results of our analysis.

Original languageEnglish (US)
Pages (from-to)681-690
Number of pages10
JournalJournal of neuroscience research
Volume68
Issue number6
DOIs
StatePublished - Jun 15 2002

Keywords

  • Amyotrophic lateral sclerosis
  • Cytoskeleton
  • Interaction forces
  • Intermediate filaments
  • Phosphorylation
  • Unstructured proteins

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

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