Lateral signaling mediated by axon contact and calcium entry regulates asymmetric odorant receptor expression in C. elegans

Cell. 1999 Nov 12;99(4):387-98. doi: 10.1016/s0092-8674(00)81525-1.


C. elegans detects several odorants with the bilaterally symmetric pair of AWC olfactory neurons. A stochastic, coordinated decision ensures that the candidate odorant receptor gene str-2 is expressed in only one AWC neuron in each animal--either the left or the right neuron, but never both. An interaction between the two AWC neurons generates asymmetric str-2 expression in a process that requires normal axon guidance and probably AWC axon contact. This interaction induces str-2 expression by reducing calcium signaling through a voltage-dependent Ca2+ channel and the CaM kinase II UNC-43. CaMKII activity acts as a switch in the initial decision to express str-2; thus, calcium signals can define distinct cell types during neuronal development. A cGMP signaling pathway that is used in olfaction maintains str-2 expression after the initial decision has been made.

Publication types

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

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Axons / metabolism*
  • Axons / physiology
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Calcium / metabolism*
  • Calcium Signaling*
  • Gene Expression Regulation, Developmental
  • Molecular Sequence Data
  • Mutation
  • Neurons / metabolism
  • Receptors, Odorant / biosynthesis*
  • Receptors, Odorant / genetics
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / genetics


  • Receptors, Odorant
  • Recombinant Fusion Proteins
  • Str-2 protein, C elegans
  • Calcium

Associated data

  • GENBANK/AF216966