The C. elegans homeodomain gene unc-42 regulates chemosensory and glutamate receptor expression.
Genes that specify cell fate can influence multiple aspects of neuronal differentiation, including axon guidance, target selection and synapse formation. Mutations in the unc-42 gene disrupt axon guidance along the C. elegans ventral nerve cord and cause distinct functional defects in sensory-locomotory neural circuits. Here we show that unc-42 encodes a novel homeodomain protein that specifies the fate of three classes of neurons in the Caenorhabditis elegans nervous system: the ASH polymodal sensory neurons, the AVA, AVD and AVE interneurons that mediate repulsive sensory stimuli to the nematode head and anterior body, and a subset of motor neurons that innervate head and body-wall muscles. unc-42 is required for the expression of cell-surface receptors that are essential for the mature function of these neurons. In mutant animals, the ASH sensory neurons fail to express SRA-6 and SRB-6, putative chemosensory receptors. The AVA, AVD and AVE interneurons and RME and RMD motor neurons of unc-42 mutants similarly fail to express the GLR-1 glutamate receptor. These results show that unc-42 performs an essential role in defining neuron identity and contributes to the establishment of neural circuits in C. elegans by regulating the transcription of glutamate and chemosensory receptor genes.
Baran
R
R
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3204, USA.
Aronoff
R
R
Garriga
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D002628:Chemoreceptor Cells; D018509:DNA, Helminth; D005786:Gene Expression Regulation; D017238:Genes, Helminth; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007395:Interneurons / Q000166:cytology; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009046:Motor Neurons / Q000166:cytology; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000235:genetics*; D011817:Rabbits; D018091:Receptors, AMPA / Q000235:genetics*; D017470:Receptors, Glutamate
D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D015801:Helminth Proteins; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; C096470:glr-1 protein, C elegans; C119682:unc-42 protein, C elegans