Hobert O, Mori I, Yamashita Y, Honda H, Ohshima Y, Liu Y, Ruvkun G
Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
Neuron. 1997 Aug;19(2):345-57. doi: 10.1016/s0896-6273(00)80944-7.
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.
神经通路将温度感应神经元与运动和自主输出相连接,使动物能够在面对经常遇到的极端温度时,通过导航远离并调节代谢率。ttx-3是秀丽隐杆线虫介导体温调节的神经通路中AIY中间神经元特化所必需的。ttx-3基因敲除突变体动物表现出与野生型中AIY激光消融所见相同的趋温行为缺陷,这表明在该突变体中AIY不发出信号。ttx-3编码一种LIM同源结构域蛋白。一个ttx-3-GFP融合基因在成年AIY中间神经元对中特异性表达,该神经元对与温度感觉神经元相连。在ttx-3突变体动物中,AIY中间神经元产生,但表现出轴突异常生长模式。因此,TTX-3 LIM同源结构域蛋白可能在AIY分化后期调节该中间神经元在体温调节通路中发挥功能所需的靶基因表达。依赖ttx-3的温度感觉通路也与温度调节的滞育神经内分泌信号通路相连,表示ttx-3指定了AIY对运动和自主输出两者的温度感觉信息处理。