Netrin UNC-6 and the regulation of branching and extension of motoneuron axons from the ventral nerve cord of Caenorhabditis elegans.

نویسندگان

  • Y S Lim
  • S Mallapur
  • G Kao
  • X C Ren
  • W G Wadsworth
چکیده

In the Caenorhabditis elegans embryo, some ventral midline motoneurons extend a process circumferentially to the dorsal midline and a process longitudinally along ventral nerve cord interneurons. Circumferential migrations are guided by netrin UNC-6, which repels motoneuron axons dorsally. Although the motoneuron cell bodies and the longitudinal axons are positioned along UNC-6-expressing interneurons in the ventral nerve cord, the circumferential processes extend only from the motoneuron cell bodies and from defined locations along some longitudinal axons. This implies a mechanism regulates motoneuron branching of UNC-6-responsive processes. We show that expression of unc-6DeltaC, which encodes UNC-6 without domain C, partially rescues circumferential migration defects in unc-6 null animals. This activity depends on the netrin receptors UNC-5 and UNC-40. These results indicate that UNC-6DeltaC can provide the circumferential guidance functions of UNC-6. Furthermore, we show that expression of unc-6DeltaC causes motoneuron branching and the extension of processes from abnormal positions along the ventral nerve cord. This activity is also UNC-5- and UNC-40-dependent. We propose that local interactions mediated by domain C regulate motoneuron branching and responsiveness to the UNC-6 cue.

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عنوان ژورنال:
  • The Journal of neuroscience : the official journal of the Society for Neuroscience

دوره 19 16  شماره 

صفحات  -

تاریخ انتشار 1999