BACKGROUND After axon severing, neurons recover function by reinitiating axon outgrowth. New outgrowth often originates from the remaining axon stump. However, in many mammalian neurons, new axons initiate from a dendritic site when the axon is injured close to the cell body. METHODS Drosophila sensory neurons are ideal for studying neuronal injury responses because they can be injured reproducibly in a variety of genetic backgrounds. In Drosophila, it has been shown that a complex sensory neuron, ddaC, can regenerate an axon from a stump, and a simple sensory neuron, ddaE, can regenerate an axon from a dendrite. To provide a more complete picture of axon regeneration in these cell types, we performed additional injury types. RESULTS We found that ddaE neurons can initiate regeneration from an axon stump when a stump remains. We also showed that ddaC neurons regenerate from the dendrite when the axon is severed close to the cell body. We next demonstrated if a stump remains, new axons can originate from this site and a dendrite at the same time. Because cutting the axon close to the cell body results in growth of the new axon from a dendrite, and cutting further out may not, we asked whether the initial response in the cell body was similar after both types of injury. A transcriptional reporter for axon injury signaling, puc-GFP, increased with similar timing and levels after proximal and distal axotomy. However, changes in dendritic microtubule polarity differed in response to the two types of injury, and were influenced by the presence of a scar at the distal axotomy site. CONCLUSIONS We conclude that both ddaE and ddaC can regenerate axons either from the stump or a dendrite, and that there is some feedback between the two sites that modulates dendritic microtubule polarity.

中文翻译：

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两个果蝇模型神经元可以从树桩或转换后的树突再生轴突，并在两个部位之间产生反馈。

背景技术轴突切断后，神经元通过重新启动轴突生长来恢复功能。新的生长通常来自剩余的轴突残端。但是，在许多哺乳动物神经元中，当轴突靠近细胞体受伤时，新的轴突从树突部位开始。方法果蝇感觉神经元是研究神经元损伤反应的理想选择，因为它们可以在多种遗传背景下可再现地受到损伤。在果蝇中，已经表明，复杂的感觉神经元ddaC可以从树桩再生轴突，而简单的感觉神经元ddaE可以从树突再生轴突。为了提供这些细胞类型中轴突再生的更完整图片，我们进行了其他损伤类型。结果我们发现ddaE神经元可以在残端残存时启动轴突残端的再生。我们还显示，当轴突靠近细胞体时，ddaC神经元从树突再生。接下来，我们演示了如果还剩下一个树桩，则可以同时从该位置和树突中产生新的轴突。因为将轴突切割得靠近细胞体会导致新的轴突从树突状细胞中生长出来，而进一步切割可能不会，因此我们询问两种损伤后细胞体内的初始反应是否相似。轴突损伤信号转导的转录报告基因puc-GFP在近端和远端轴索切开术后以相似的时间和水平增加。但是，树突状微管极性的变化对这两种损伤有不同的反应，并且受远端轴突切开处疤痕的存在影响。