Signaling mechanisms of non-conventional axon guidance cues: the Shh, BMP and Wnt morphogens

Curr Opin Neurobiol. 2013 Dec;23(6):965-73. doi: 10.1016/j.conb.2013.09.002. Epub 2013 Oct 29.


During nervous system development, axons, led by the growth cone, must navigate to their destinations. Axon guidance cues are molecules in the extracellular environment that attract or repel axons to guide them along their correct trajectory. The non-conventional axon guidance cues include morphogens of the Hedgehog, TGF-β/BMP, and Wnt/Wgl families. Canonical signaling by morphogens regulates transcription in the nucleus to specify cell fate. Recent studies have begun to elucidate how these morphogens can also direct growth cone turning, using signaling mechanisms that diverge from their canonical signaling pathways. Furthermore, in addition to directly guiding axons, some non-conventional guidance cues such as Sonic hedgehog also modulate the response of axons to other guidance cues, adding another level of regulation to axon guidance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Axons / metabolism*
  • Bone Morphogenetic Proteins / metabolism*
  • Hedgehog Proteins / metabolism*
  • Humans
  • Neurogenesis / physiology*
  • Signal Transduction / physiology*
  • Wnt Proteins / metabolism*


  • Bone Morphogenetic Proteins
  • Hedgehog Proteins
  • Wnt Proteins