Concentration-dependent requirement for local protein synthesis in motor neuron subtype-specific response to axon guidance cues.
Concentration-dependent requirement for local protein synthesis in motor neuron subtype-specific response to axon guidance cues.
复制标题
DOI：
10.1523/jneurosci.4176-11.2012
复制
发表时间：
2012-01-25
期刊：
影响因子：
--
通讯作者：
Wichterle H
中科院分区：
文献类型：
--
作者：
Nédelec S;Peljto M;Shi P;Amoroso MW;Kam LC;Wichterle H
功能性运动回路的形成依赖于不同的脊髓运动神经元亚型以高精度将其轴突投射到适当的肌肉靶点的能力。虽然已经确定了有助于运动轴突寻路的指导线索，但对这些线索的亚型特异性反应的细胞内途径仍然知之甚少。特别是，它仍然是有争议的轴突导向线索的反应是否依赖于轴突蛋白质的合成。利用生长锥塌陷实验，我们证明了小鼠胚胎干细胞（ESC）衍生的脊髓运动神经元（ES-MN）的ephrin-A5，Sema 3f和Sema 3a的浓度依赖性的方式。在低剂量下，ES-MN表现出节段性或亚型特异性反应，而这种选择性在较高浓度下丧失。对高剂量的脑信号蛋白和所有剂量的肝配蛋白-A5的反应是蛋白质合成独立的。相比之下，使用微流控装置和条纹测定，我们表明，生长锥崩溃和指导在低浓度的信号蛋白依赖于局部蛋白质合成的轴突室。在人类ES-MN中观察到对低浓度和高浓度的指导线索的类似双峰反应，指出神经元增加其对参与神经回路形成的有限指导线索的反应库的一般机制。
Formation of functional motor circuits relies on the ability of distinct spinal motor neuron subtypes to project their axons with high precision to appropriate muscle targets. While guidance cues contributing to motor axon pathfinding have been identified, the intracellular pathways underlying subtype specific responses to these cues remain poorly understood. In particular, it remains controversial whether responses to axon guidance cues depend on axonal protein synthesis. Using a growth cone collapse assay, we demonstrate that mouse embryonic stem cell (ESC) derived spinal motor neurons (ES-MNs) respond to ephrin-A5, Sema3f and Sema3a in a concentration dependent manner. At low doses, ES-MNs exhibit segmental or subtype specific responses, while this selectivity is lost at higher concentrations. Response to high doses of semaphorins and to all doses of ephrin-A5 is protein synthesis independent. In contrast, using microfluidic devices and stripe assays, we show that growth cone collapse and guidance at low concentrations of semaphorins relies on local protein synthesis in the axonal compartment. Similar bimodal response to low and high concentrations of guidance cues is observed in human ES-MNs, pointing to a general mechanism by which neurons increase their repertoire of responses to the limited set of guidance cues involved in neural circuit formation.