title: The fax-1 nuclear hormone receptor regulates axon pathfinding and neurotransmitter expression.
abstract: Specification of neuron identity requires the activation of a number of discrete developmental programs. Among these is pathway selection by growth cones: in order for a neuron's growth cone to respond appropriately to guidance cues presented by other cells or the extracellular matrix, the neuron must express genes to mediate the response. The fax-1 gene of C. elegans is required for pathfinding of axons that extend along the ventral nerve cord. We show that fax-1 is also required for pathfinding of axons in the nerve ring, the largest nerve bundle in the nematode, and for normal expression of FMRFamide-like neurotransmitters in the AVK interneurons. The fax-1 gene encodes a member of the superfamily of nuclear hormone receptors and has a DNA-binding domain related to the human PNR and Drosophila Tailless proteins. We observe fax-1 expression in embryonic neurons, including the AVK interneurons, just prior to axon extension, but after neurogenesis. These data suggest that fax-1 coordinately regulates the transcription of genes that function in the selection of axon pathways, neurotransmitter expression and, perhaps, other aspects of the specification of neuron identity.
authors.affiliation: Biology Department, Muhlenberg College, Allentown, PA 18104, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Much
authors.forename: D J
authors.initials: DJ
authors.lastname: Slade
authors.forename: K
authors.initials: K
authors.lastname: Klampert
authors.forename: G
authors.initials: G
authors.lastname: Garriga
authors.forename: B
authors.initials: B
authors.lastname: Wightman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000378:metabolism*; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D020439:Growth Cones / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009420:Nervous System / Q000254:growth & development / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010802:Phylogeny; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; C405022:FAX-1 protein, C elegans; D018377:Neurotransmitter Agents; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear