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Congenital hypomyelinating neuropathy with lethal conduction failure in mice carrying the Egr2 I268N mutation.

Mouse models of human disease are helpful for understanding the pathogenesis of the disorder and ultimately for testing potential therapeutic agents. Here, we describe the engineering and characterization of a mouse carrying the I268N mutation in Egr2, observed in patients with recessively inherited Charcot-Marie-Tooth (CMT) disease type 4E, which is predicted to alter the ability of Egr2 to interact with the Nab transcriptional coregulatory proteins. Mice homozygous for Egr2(I268N) develop a congenital hypomyelinating neuropathy similar to their human counterparts. Egr2(I268N) is expressed at normal levels in developing nerve but is unable to interact with Nab proteins or to properly activate transcription of target genes critical for proper peripheral myelin development. Interestingly, Egr2(I268N/I268N) mutant mice maintain normal weight and have only mild tremor until 2 weeks after birth, at which point they rapidly develop worsening weakness and uniformly die within several days. Nerve electrophysiology revealed conduction block, and neuromuscular junctions showed marked terminal sprouting similar to that seen in animals with pharmacologically induced blockade of action potentials or neuromuscular transmission. These studies describe a unique animal model of CMT, whereby weakness is due to conduction block or neuromuscular junction failure rather than secondary axon loss and demonstrate that the Egr2-Nab complex is critical for proper peripheral nerve myelination.

Pubmed ID: 19244508

Authors

  • Baloh RH
  • Strickland A
  • Ryu E
  • Le N
  • Fahrner T
  • Yang M
  • Nagarajan R
  • Milbrandt J

Journal

The Journal of neuroscience : the official journal of the Society for Neuroscience

Publication Data

February 25, 2009

Associated Grants

  • Agency: NINDS NIH HHS, Id: 1K08NS055980
  • Agency: NIDA NIH HHS, Id: 5-T32-DA07261
  • Agency: NINDS NIH HHS, Id: NS040745
  • Agency: NINDS NIH HHS, Id: NS057105
  • Agency: NINDS NIH HHS, Id: R01 NS040745
  • Agency: NINDS NIH HHS, Id: R01 NS040745-04
  • Agency: NINDS NIH HHS, Id: R01 NS040745-05

Mesh Terms

  • Animals
  • Asparagine
  • Cell Line, Transformed
  • Cell Proliferation
  • Charcot-Marie-Tooth Disease
  • Cranial Nerve Diseases
  • Disease Models, Animal
  • Early Growth Response Protein 2
  • Humans
  • Immunoprecipitation
  • Isoleucine
  • Mice
  • Mice, Transgenic
  • Microscopy, Electron, Transmission
  • Myelin Proteins
  • Neoplasm Proteins
  • Neural Conduction
  • Ranvier's Nodes
  • Repressor Proteins
  • Schwann Cells
  • Sciatic Nerve