Tanaka Daisuke, Nakaya Yohei, Yanagawa Yuchio, Obata Kunihiko, Murakami Fujio
Graduate School of Frontier Biosciences, Osaka University, Machikaneyama 1-3, Toyonaka, Osaka 560-8531, Japan.
Development. 2003 Dec;130(23):5803-13. doi: 10.1242/dev.00825. Epub 2003 Oct 8.
Neuronal migration is crucial for the construction of neuronal architecture such as layers and nuclei. Most inhibitory interneurons in the neocortex derive from the basal forebrain and migrate tangentially; however, little is known about the mode of migration of these neurons in the cortex. We used glutamate decarboxylase (Gad)67-green fluorescent protein (GFP) knock-in embryonic mice with expression of GFP in gamma-aminobutyric acid (GABA)-ergic neurons and performed time-lapse analysis. In coronal slices, many GFP-positive neurons in the lower intermediate zone (IZ) and subventricular zone (SVZ) showed robust tangential migration from lateral to medial cortex, while others showed radial and non-radial migration mostly towards the pial surface. In flat-mount preparations, GFP-positive neurons of the marginal zone (MZ) showed multidirectional tangential migration. Some of these neurons descended toward the cortical plate (CP). Intracortical migration of these neurons was largely unaffected by a treatment that cleaves glycosylphosphatidylinositol (GPI) anchors. These findings suggest that tangential migration of cortical interneurons from lateral to medial cortex predominantly occurs in the IZ/SVZ and raise the possibility that a part of the pial surface-directed neurons in the IZ/SVZ reach the MZ, whereby they spread into the whole area of the cortex. At least a part of these neurons may descend toward the CP. Our results also suggest that intracortical migration of GABAergic neurons occurs independent of GPI-anchored proteins.
神经元迁移对于构建诸如层和核等神经元结构至关重要。新皮层中的大多数抑制性中间神经元起源于基底前脑并进行切向迁移；然而，对于这些神经元在皮层中的迁移方式知之甚少。我们使用了谷氨酸脱羧酶（Gad）67 - 绿色荧光蛋白（GFP）基因敲入的胚胎小鼠，其中GFP在γ-氨基丁酸（GABA）能神经元中表达，并进行了延时分析。在冠状切片中，位于下部中间带（IZ）和脑室下区（SVZ）的许多GFP阳性神经元显示出从外侧向内侧皮层的强劲切向迁移，而其他神经元则显示出主要朝向软脑膜表面的径向和非径向迁移。在平铺标本中，边缘带（MZ）的GFP阳性神经元显示出多方向的切向迁移。其中一些神经元向皮质板（CP）下降。这些神经元的皮质内迁移在很大程度上不受切割糖基磷脂酰肌醇（GPI）锚的处理的影响。这些发现表明，皮质中间神经元从外侧向内侧皮层的切向迁移主要发生在IZ/SVZ，并增加了IZ/SVZ中一部分朝向软脑膜表面的神经元到达MZ的可能性，从而它们扩散到整个皮层区域。这些神经元中至少有一部分可能向CP下降。我们的结果还表明，GABA能神经元的皮质内迁移独立于GPI锚定蛋白发生。
