Li Wei, Feng Zhaoyang, Sternberg Paul W, Xu X Z Shawn
Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
Nature. 2006 Mar 30;440(7084):684-7. doi: 10.1038/nature04538.
The nematode Caenorhabditis elegans is commonly used as a genetic model organism for dissecting integration of the sensory and motor systems. Despite extensive genetic and behavioural analyses that have led to the identification of many genes and neural circuits involved in regulating C. elegans locomotion behaviour, it remains unclear whether and how somatosensory feedback modulates motor output during locomotion. In particular, no stretch receptors have been identified in C. elegans, raising the issue of whether stretch-receptor-mediated proprioception is used by C. elegans to regulate its locomotion behaviour. Here we have characterized TRP-4, the C. elegans homologue of the mechanosensitive TRPN channel. We show that trp-4 mutant worms bend their body abnormally, exhibiting a body posture distinct from that of wild-type worms during locomotion, suggesting that TRP-4 is involved in stretch-receptor-mediated proprioception. We show that TRP-4 acts in a single neuron, DVA, to mediate its function in proprioception, and that the activity of DVA can be stimulated by body stretch. DVA both positively and negatively modulates locomotion, providing a unique mechanism whereby a single neuron can fine-tune motor activity. Thus, DVA represents a stretch receptor neuron that regulates sensory-motor integration during C. elegans locomotion.
线虫秀丽隐杆线虫通常被用作一种遗传模型生物，用于剖析感觉和运动系统的整合。尽管进行了广泛的遗传和行为分析，已鉴定出许多参与调节秀丽隐杆线虫运动行为的基因和神经回路，但尚不清楚在运动过程中体感反馈是否以及如何调节运动输出。特别是，在秀丽隐杆线虫中尚未鉴定出拉伸受体，这就引发了一个问题，即秀丽隐杆线虫是否利用拉伸受体介导的本体感觉来调节其运动行为。在这里，我们对机械敏感的TRPN通道的秀丽隐杆线虫同源物TRP-4进行了表征。我们发现trp-4突变体蠕虫身体弯曲异常，在运动过程中表现出与野生型蠕虫不同的身体姿势，这表明TRP-4参与拉伸受体介导的本体感觉。我们发现TRP-4在单个神经元DVA中发挥作用，以介导其在本体感觉中的功能，并且DVA的活性可以通过身体拉伸来刺激。DVA对运动起到正向和负向调节作用，提供了一种独特的机制，即单个神经元可以微调运动活动。因此，DVA代表了一种在秀丽隐杆线虫运动过程中调节感觉-运动整合的拉伸受体神经元。
