Myocilin mediates myelination in the peripheral nervous system through ErbB2/3 signaling

J Biol Chem. 2013 Sep 13;288(37):26357-71. doi: 10.1074/jbc.M112.446138. Epub 2013 Jul 29.

Abstract

The glaucoma-associated gene, myocilin, is expressed in ocular and non-ocular tissues including the peripheral nervous system, but its functions in these tissues remain poorly understood. We demonstrate that in sciatic nerve, myocilin is expressed in Schwann cells with high concentrations at the nodes of Ranvier. There, myocilin interacts with gliomedin, neurofascin, and NrCAM, which are essential for node formation and function. Treatment of isolated dorsal root ganglion cultures with myocilin stimulates clustering of the nodal proteins neurofascin and sodium channel Nav1.2. Sciatic nerves of myocilin null mice express reduced levels of several myelin-associated and basal membrane proteins compared with those of wild-type littermates. They also demonstrate reduced myelin sheath thickness and partial disorganization of the nodes. Myocilin signaling through ErbB2/3 receptors may contribute to these observed effects. Myocilin binds to ErbB2/ErbB3, activates these receptors, and affects the downstream PI3K-AKT signaling pathway. These data implicate a role for myocilin in the development and/or maintenance of myelination and nodes of Ranvier in sciatic nerve.

Keywords: Epidermal Growth Factor Receptor (EGFR); Glaucoma; Glycoprotein Secretion; Myelin; Myocilin; Node of Ranvier; Schwann Cells; Sciatic Nerve; Signaling.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • Ganglia, Spinal / metabolism
  • Gene Expression Regulation
  • Glaucoma / metabolism
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Confocal
  • Mutation
  • Myelin Sheath / genetics
  • Myelin Sheath / metabolism*
  • Peripheral Nervous System / metabolism*
  • Phosphorylation
  • Ranvier's Nodes / metabolism
  • Receptor, ErbB-2 / metabolism*
  • Receptor, ErbB-3 / metabolism*
  • Sciatic Nerve / metabolism
  • Signal Transduction

Substances

  • Cytoskeletal Proteins
  • Eye Proteins
  • Glycoproteins
  • trabecular meshwork-induced glucocorticoid response protein
  • Receptor, ErbB-2
  • Receptor, ErbB-3