Pla Ramón, Borrell Víctor, Flames Nuria, Marín Oscar
Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas and Universidad Miguel Hernández, 03550 Sant Joan d'Alacant, Spain.
J Neurosci. 2006 Jun 28;26(26):6924-34. doi: 10.1523/JNEUROSCI.0245-06.2006.
Functioning of the cerebral cortex requires the coordinated assembly of circuits involving glutamatergic projection neurons and GABAergic interneurons. Despite their segregated origin in different regions of the telencephalon, projection neurons and interneurons born synchronically end up adopting the same cortical layer, suggesting that layer acquisition is highly coordinated for both neuronal types. The radial migration and laminar arrangement of projection neurons depends on Reelin, a secreted glycoprotein expressed near the pial surface during embryogenesis. In contrast, the mechanisms controlling layer acquisition by cortical interneurons remain essentially unknown. Here, we have used an ultrasound-guided transplantation approach to analyze the mechanisms underlying the acquisition of laminar locations by cortical interneurons. We found that layer acquisition by cortical GABAergic interneurons does not directly depend on Reelin signaling. Moreover, interneurons invade their target layers well after synchronically generated projection neurons reach their final destination. These results suggest a model in which cues provided by projection neurons guide cortical interneurons to their appropriate layer, and reveal that, at least for some neuronal types, long-range radial migration does not directly require Reelin.
大脑皮层的功能需要由谷氨酸能投射神经元和γ-氨基丁酸能中间神经元组成的回路进行协调组装。尽管投射神经元和中间神经元起源于端脑的不同区域，但同步产生的这类神经元最终会进入同一皮层层，这表明两种神经元类型的层定位高度协调。投射神经元的径向迁移和层状排列依赖于Reelin，这是一种在胚胎发育过程中于软膜表面附近表达的分泌型糖蛋白。相比之下，控制皮层中间神经元层定位的机制基本上仍不清楚。在这里，我们使用了超声引导移植方法来分析皮层中间神经元获得层状位置的潜在机制。我们发现，皮层γ-氨基丁酸能中间神经元的层定位并不直接依赖于Reelin信号。此外，在同步产生的投射神经元到达其最终目的地后很久，中间神经元才侵入其目标层。这些结果提示了一种模型，即投射神经元提供的线索引导皮层中间神经元到达其合适的层，并揭示出，至少对于某些神经元类型来说，远距离径向迁移并不直接需要Reelin。
