Forced expression of Phox2 homeodomain transcription factors induces a branchio-visceromotor axonal phenotype

Dev Biol. 2007 Mar 15;303(2):687-702. doi: 10.1016/j.ydbio.2006.12.006. Epub 2006 Dec 15.


What causes motor neurons to project into the periphery is not well understood. We here show that forced expression of the homeodomain protein Phox2b, shown previously to be necessary and sufficient for branchio-visceromotor neuron development, and of its paralogue Phox2a imposes a branchiomotor-like axonal phenotype in the spinal cord. Many Phox2-transfected neurons, whose axons would normally stay within the confines of the neural tube, now project into the periphery. Once outside the neural tube, a fraction of the ectopic axons join the spinal accessory nerve, a branchiomotor nerve which, as shown here, does not develop in the absence of Phox2b. Explant studies show that the axons of Phox2-transfected neurons need attractive cues to leave the neural tube and that their outgrowth is promoted by tissues, to which branchio-visceromotor fibers normally grow. Hence, Phox2 expression is a key step in determining the peripheral axonal phenotype and thus the decision to stay within the neural tube or to project out of it.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accessory Nerve / cytology
  • Accessory Nerve / embryology
  • Accessory Nerve / metabolism
  • Animals
  • Animals, Genetically Modified
  • Axons / metabolism
  • Chick Embryo
  • Gene Expression Regulation, Developmental
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Mice
  • Mice, Mutant Strains
  • Mice, Transgenic
  • Motor Neurons / cytology
  • Motor Neurons / metabolism*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Phenotype
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transfection


  • Homeodomain Proteins
  • NBPhox protein
  • Nerve Tissue Proteins
  • Transcription Factors