Mechanisms of the development of neuronal cell society in the central nervous system

在发育中的大脑皮质中，大多数出生在脑室附近的神经元作为多极迁移神经元聚集在脑室下区(SVZ)，然后在进入皮质板(CP)之前转化为运动神经元。当运动细胞到达边缘带(MZ)以下的层时，我们观察到除了终止迁移外，它们还经历了各种戏剧性的形态变化。例如，它们开始发育顶端原始树突并聚集在MZ下方，这表明它们可能开始与相邻细胞形成新的细胞间关系，从而形成适当的层结构。此外，CP内由放射状胶质纤维引导的运动神经元，一旦其前导突起到达软膜表面，最终经历胞体移位(“终末移位”)。为了了解调控这些事件的机制，我们在这项研究中采取了几种方法。首先，我们筛选了在胚胎皮质壁的每个区域的细胞中特异表达的基因：脑室区(VZ)、SVZ或MZ下的细胞。因此，我们确定了大约4000个在VZ中优先表达的基因，其中659个基因是分泌或跨膜分子。对于SVZ和MZ下的细胞，我们分别发现约20个基因和40个基因在每个区域优先表达。在这项研究中，我们分析了其中一些基因的生物学功能。以迁徙阶段依赖的方式阐明这些分子基因表达谱的调控机制将在未来的研究中发挥重要作用。

In the developing cerebral cortex, most neurons that are born near the ventricle accumulate in the subventricular zone (SVZ) as multipolar migrating neurons and are then transformed to locomoting neurons prior to entering the cortical plate (CP). When the locomoting cells reach the layer beneath the marginal zone (MZ), we observed that they undergo various dramatic morphological changes, in addition to the termination of migration. For example, they begin to develop apical primitive dendrites and accumulate beneath the MZ, suggesting that they probably start to form new intercellular relationships with adjacent cells and thereby develop an appropriate layer structure. Furthermore, locomoting neurons guided by radial glial fibers in the CP ultimately undergo somal translocation once their leading processes reach the pial surface ("terminal translocation"). To understand the mechanisms that regulate these events, we took several approaches in this study. Firstly, we screened for genes that are specifically expressed in cells in each zone of the embryonic cortical wall: ventricular zone (VZ), SVZ, or cells beneath the MZ. Consequently, we identified approximately 4, 000 genes that are preferentially expressed in the VZ, among which 659 genes are secretory or transmembrane molecules. As for the SVZ and the cells beneath the MZ, we found about 20 genes and 40 genes expressed preferentially in each zone, respectively. We have analyzed the biological functions of some of these genes in this study. To clarify the regulatory mechanisms of gene expression profiles of these molecules in a migratory stage-dependent manner would be important in the future study.