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

Yoo Shick Lim, Smita Mallapur, Gautam Kao, Xing Cong Ren, William G. Wadsworth

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

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-6ΔC, 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-6ΔC can provide the circumferential guidance functions of UNC-6. Furthermore, we show that expression of unc-6ΔC 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.

Original languageEnglish (US)
Pages (from-to)7048-7056
Number of pages9
JournalJournal of Neuroscience
Volume19
Issue number16
DOIs
StatePublished - Aug 15 1999

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Keywords

  • Axon branching
  • C. elegans
  • Genetics
  • Guidance
  • In vivo
  • Invertebrate
  • Netrin
  • UNC-6

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