Regulation of interneuron function in the C. elegans thermoregulatory pathway by the ttx-3 LIM homeobox gene.
Neural pathways, which couple temperature-sensing neurons to motor and autonomic outputs, allow animals to navigate away from and adjust metabolism rates in response to the temperature extremes often encountered. ttx-3 is required for the specification of the AIY interneuron in the C. elegans neural pathway that mediates thermoregulation. ttx-3 null mutant animals exhibit the same thermotactic behavioral defect as that seen with laser ablation of AIY in wild type, suggesting that AIY does not signal in this mutant. ttx-3 encodes a LIM homeodomain protein. A ttx-3-GFP fusion gene is expressed specifically in the adult AIY interneuron pair, which connects to thermosensory neurons. In ttx-3 mutant animals, the AIY interneuron is generated but exhibits patterns of abnormal axonal outgrowth. Thus, the TTX-3 LIM homeodomain protein is likely to regulate the expression of target genes required late in AIY differentiation for the function of this interneuron in the thermoregulatory pathway. The ttx-3-dependent thermosensory pathway also couples to the temperature-modulated dauer neuroendocrine signaling pathway, showing that ttx-3 specifies AIY thermosensory information processing of both motor and autonomic outputs.
Hobert
O
O
Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
Mori
I
I
Yamashita
Y
Y
Honda
H
H
Ohshima
Y
Y
Liu
Y
Y
Ruvkun
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D005801:Genes, Homeobox / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D007395:Interneurons / Q000502:physiology*; D008969:Molecular Sequence Data; D009434:Neural Pathways / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; D018398:Homeodomain Proteins; D009479:Neuropeptides; C108368:TTX-3 protein, C elegans