Lateral signaling mediated by axon contact and calcium entry regulates asymmetric odorant receptor expression in C. elegans.
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.
Troemel
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Howard Hughes Medical Institute, Department of Anatomy, The University of California, San Francisco 94143-0452, USA.
Sagasti
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Bargmann
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D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000378:metabolism* / Q000502:physiology; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D018035:Receptors, Odorant / Q000096:biosynthesis* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics
D018035:Receptors, Odorant; D011993:Recombinant Fusion Proteins; C514941:Str-2 protein, C elegans; D002118:Calcium