Elongation of axons during regeneration involves retinal crystallin beta b2 (crybb2)

Mol Cell Proteomics. 2007 May;6(5):895-907. doi: 10.1074/mcp.M600245-MCP200. Epub 2007 Jan 29.


Adult retinal ganglion cells (RGCs) can regenerate their axons in vitro. Using proteomics, we discovered that the supernatants of cultured retinas contain isoforms of crystallins with crystallin beta b2 (crybb2) being clearly up-regulated in the regenerating retina. Immunohistochemistry revealed the expression of crybb within the retina, including in filopodial protrusions and axons of RGCs. Cloning and overexpression of crybb2 in RGCs and hippocampal neurons increased axonogenesis, which in turn could be blocked with antibodies against beta-crystallin. Conditioned medium from crybb2-transfected cell cultures also supported the growth of axons. Finally real time imaging of the uptake of green fluorescent protein-tagged crybb2 fusion protein showed that this protein becomes internalized. These data are the first to show that axonal regeneration is related to crybb2 movement. The results suggest that neuronal crystallins constitute a novel class of neurite-promoting factors that likely operate through an autocrine mechanism and that they could be used in neurodegenerative diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Axons / physiology*
  • Callithrix
  • Cell Culture Techniques
  • Cell Line
  • Cells, Cultured
  • Culture Media
  • Electrophoresis, Gel, Two-Dimensional
  • Growth Cones / physiology
  • Molecular Sequence Data
  • Protein Isoforms / chemistry
  • Protein Isoforms / physiology
  • Proteomics
  • Rats
  • Rats, Sprague-Dawley
  • Retina / cytology
  • Retinal Ganglion Cells
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • beta-Crystallin B Chain / chemistry
  • beta-Crystallin B Chain / physiology*


  • Culture Media
  • Protein Isoforms
  • beta-Crystallin B Chain
  • beta-crystallin B2