The influence of pioneer neurons on a growing motor nerve in Drosophila requires the neural cell adhesion molecule homolog FasciclinII
The influence of pioneer neurons on a growing motor nerve in Drosophila requires the neural cell adhesion molecule homolog FasciclinII
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DOI：
10.1523/jneurosci.2377-04.2005
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发表时间：
2005-01-05
影响因子：
5.3
通讯作者：
Prokop, A
中科院分区：
文献类型：
--
作者：
S치nchez-Soriano, N;Prokop, A
先驱神经元现象为人所知已近一个世纪，但迄今为止我们对所涉及的机制和分子知之甚少。在这里，我们研究果蝇节间运动神经（ISN）的形成。我们发现 aCC/RP2 和 U 运动神经元在 ISN 的前沿一起生长。尽管如此，aCC/RP2 神经元是先驱，U 神经元是追随者，因为只有 aCC/RP2 神经元有效影响 ISN 的生长。我们还表明，这种影响取决于神经细胞粘附分子同系物 FasciclinII。首先，aCC/RP2 的消融对 ISN 生长的影响比 U 消融更大。其次，我们使用的失速方法揭示了 aCC/RP2 强大的生长影响能力：当 aCC/RP2 运动轴突特别失速时，整个 ISN（包括 U 神经元）共同协调，表明 aCC/RP2 神经元影响 U 生长锥的行为。相比之下，停滞的 U 神经元对其他 ISN 运动神经元没有同样的影响。对 ISN 生长的影响需要 FasciclinII：U 神经元中 FasciclinII 的靶向表达增加了它们对 ISN 的影响，而 FasciclinII 功能丧失背景则减少了 ISN 与停滞的 aCC/RP2 轴突的协调。我们的研究结果证实了两个神经元组的质量差异，即 aCC/RP2 生长锥比 U 神经元的生长锥更宽、更复杂。然而，在 FasciclinII 功能丧失背景下，U 生长锥采用类似 aCC/RP2 的更宽形状。因此，FasciclinII 在一定程度上是先锋追随者相互作用所必需和充分的，但其作用模式不能仅仅通过同样的双向粘附相互作用来解释。
The phenomenon of pioneer neurons has been known for almost a century, but so far we have little insights into mechanisms and molecules involved. Here, we study the formation of the Drosophila intersegmental motor nerve (ISN). We show that aCC/RP2 and U motor neurons grow together at the leading front of the ISN. Nevertheless, aCC/RP2 neurons are the pioneers, and U neurons are the followers, because only aCC/RP2 neurons effectively influence growth of the ISN. We also show that this influence depends on the neural cell adhesion molecule homolog FasciclinII. First, ablation of aCC/RP2 has a stronger impact on ISN growth than U ablation. Second, strong growth-influencing capabilities of aCC/RP2 are revealed with a stalling approach we used: when aCC/RP2 motor axons are stalled specifically, the entire ISN ( including the U neurons) coarrests, demonstrating that aCC/RP2 neurons influence the behavior of U growth cones. In contrast, stalled U neurons do not have the same influence on other ISN motor neurons. The influence on ISN growth requires FasciclinII: targeted expression of FasciclinII in U neurons increases their influence on the ISN, whereas a FasciclinII loss-of-function background reduces ISN coarrest with stalled aCC/RP2 axons. The qualitative differences of both neuron groups are confirmed through our findings that aCC/RP2 growth cones are wider and more complex than those of U neurons. However, U growth cones adopt aCC/RP2-like wider shapes in a FasciclinII loss-of-function background. Therefore, FasciclinII is to a degree required and sufficient for pioneer follower interactions, but its mode of action cannot be explained merely through an equally bidirectional adhesive interaction.